Fixing a parent’s “storage almost full” Mac in about ten minutes

By Mohit Nippanikar, who makes SiftMac

Someone’s Mac keeps saying “Your disk is almost full”, and you’re the one in the family who fixes things. On a parent’s Mac the space is usually in the same few places: old iPhone backups, years of downloads, the Trash, and photos and videos from Messages. Most of it can be cleared in about ten minutes with what’s already on the Mac, as long as you know which parts are theirs to keep.

1. Look before you delete

Open System Settings › General › Storage and give the bar a minute to finish counting. The list below it shows each group with its size, and ⓘ next to a group opens what’s inside. It’s often iOS Files (iPhone backups), Messages, Photos or Documents.

Two rules keep the rest safe. Ask before deleting anything that’s theirs: a download that looks like junk can be the only copy of a scanned letter. And delete each thing with the app or setting that owns it, as below, rather than by removing its folder in Finder. If they have a Time Machine drive, plug it in first and let a backup finish.

2. Old iPhone and iPad backups

If their iPhone or iPad has ever been backed up to this Mac, the backups are often the biggest single thing on it: tens of gigabytes each, and macOS never removes old ones. Storage settings lists them as iOS Files.

1. Connect their iPhone with a cable, open Finder and select the phone in the sidebar. If asked, tap Trust on the phone and enter its passcode.
2. In the General tab, click Manage Backups. The list shows the backups of every device, with their dates.
3. Keep the newest backup of each device they still use. Right-click older ones, and those of phones and iPads they no longer have, and choose Delete.

No phone to hand? System Settings › General › Storage › iOS Files › ⓘ lists the same backups; select the old ones and click Delete. A deleted backup can’t be recovered, so before removing a device’s only backup, check on the phone whether it also backs up to iCloud (Settings › their name › iCloud › iCloud Backup). The iOS software files listed there are safe to delete: Finder downloads them again when it needs one. Which backups to keep, and how to tell them apart.

3. The Trash and Downloads

Files in the Trash still take space until it’s emptied. Open it and glance through with them first, since some people keep things there on purpose, then choose Finder › Empty Trash.

Downloads is usually years of installers (.dmg, .pkg) and .zip files that have done their job. System Settings › General › Storage › Documents › ⓘ › Downloads lists them with their sizes. Installers for apps that are already installed can go. Ask about everything else: Downloads is also where tickets, statements and scanned letters end up.

4. Messages attachments

Every photo and video they’ve been sent in Messages is kept on the Mac, and a busy family group chat adds up over the years. System Settings › General › Storage › Messages › ⓘ lists the attachments with their sizes; select the ones to remove and click Delete.

Ask first, and check one setting. If Messages in iCloud is on (Messages › Settings › iMessage › Enable Messages in iCloud), deleting an attachment on the Mac also deletes it from their iPhone and iPad.

5. Photos

The Photos library is often the biggest thing on a parent’s Mac, and every picture in it is theirs. Never delete or move it in Finder. Two things are safe:

• Empty Recently Deleted. Photos keeps deleted pictures for 30 days. Choose Recently Deleted in the Photos sidebar (it may ask for their password or Touch ID), look through it with them, and click Delete All.
• Optimize Mac Storage, if they use iCloud Photos. In Photos › Settings › iCloud, select Optimize Mac Storage. The full-size originals stay in iCloud and the Mac keeps smaller copies when it’s short of space, so the space comes back gradually rather than at once.

If iCloud Photos is off, turning it on is a bigger decision: it uploads the whole library and may need a paid iCloud plan with room for it. That’s a conversation, not a ten-minute fix.

6. App caches, with the apps quit

Apps keep caches so they load faster, and make them again when they’re gone, so clearing them is safe. Quit the apps first, then in Finder choose Go › Go to Folder (⇧⌘G) and paste ~/Library/Caches. In Terminal, this lists the ten biggest folders in it, biggest last:

du -sh ~/Library/Caches/* 2>/dev/null | sort -h | tail -10

Delete what’s inside the big ones rather than the folders themselves. Caches fill up again as the apps are used, so this buys room for a while, not for good, and it’s rarely the biggest win on a parent’s Mac.

7. Time Machine snapshots: usually leave them

If they use Time Machine, macOS also keeps hourly snapshots on the Mac’s own disk, and they count toward System Data in Storage settings. To list them in Terminal:

tmutil listlocalsnapshots /

Usually, leave them. macOS counts their space as available and deletes them as they age or when something needs the room. They’re only worth removing when a macOS update refuses to install for lack of space. To remove one, use the date and time in its name, for example 2026-03-14-101500:

sudo tmutil deletelocalsnapshots <date>

Or remove all of them at once with sudo tmutil deletelocalsnapshots /. Both ask for their login password and only work from an administrator account, and neither touches the backups on their Time Machine drive. When deleting snapshots is worth it.

8. Restart, then check again

Restart the Mac: it clears temporary files and makes Storage settings count again. Give the bar a few minutes before you read it. If the space still isn’t there, Mac storage full but no files? covers the less obvious places, and the System Data guide the grey part of the bar.

9. What never to delete

• The Photos library (~/Pictures/Photos Library.photoslibrary): every photo and video they have. Remove pictures inside Photos, with them, or not at all.
• Mail (~/Library/Mail): their email. Delete mail inside Mail; Mailbox › Erase Deleted Items and Mailbox › Erase Junk Mail clear its Trash and Junk mailboxes for good.
• Documents and the Desktop: their files, often the only copy. Only they decide what goes.
• iCloud Drive (~/Library/Mobile Documents): deleting there deletes from iCloud and their other devices too.
• The newest backup of each device they still use, unless the device also backs up to iCloud.
• Anything you can’t name, in a Library folder or under /System. If you can’t tell what it’s for, leave it. Is it safe to delete? covers 40 common folders.

10. Keep it from filling again

• Empty the Trash automatically. In System Settings › General › Storage, turn on Empty Trash Automatically, which removes anything that’s been in the Trash for more than 30 days. Finder › Settings › Advanced has the same option.
• Optimize Storage, in the same place, removes films and TV shows they’ve already watched in the TV app.
• One Mac backup per device. Finder keeps one backup of each device and updates it every time, so it’s the backups of old phones that pile up. If the iPhone also backs up to iCloud, the copy on the Mac is a second one.
• Old conversations, if they agree. Messages › Settings › General › Keep messages can remove conversations older than a year, attachments included. It deletes them for good, so set it only if they’re happy to lose old chats.
• SiftMac in the menu bar, if you install it: free space at a glance, a forecast of when the disk will be full at the rate it’s filling, and Quick clean, which clears app caches only. It can also clear caches on a schedule, only when there’s at least 1 GB to free and never for apps that are open.

Questions

Will clearing their Mac delete anything on their iPhone?

Deleting an iPhone backup on the Mac doesn’t touch the iPhone. Messages and Photos are different: with Messages in iCloud or iCloud Photos on, deleting a message, attachment or photo on the Mac deletes it on their iPhone and iPad too.

Do I need Terminal for this?

No. Everything here works in System Settings, Finder, Messages and Photos. Terminal only lists Time Machine snapshots and measures cache folders, and you can skip both.

Will I need their password?

For two things. Photos may ask for their login password or Touch ID to open Recently Deleted, and deleting Time Machine snapshots with sudo asks for their login password and only works from an administrator account.