Quick answer
Delete Messages attachments through the Messages app, not by removing files from hidden Library folders. Open a conversation, click the person or group at the top, review Photos or other attachment categories, and select only items you no longer need. If Messages in iCloud is enabled, a deletion can also affect your other devices.
Why this happens
- Long-running conversations accumulate photos, videos, audio messages, and documents
- The same attachment may appear on multiple Apple devices through Messages in iCloud
- Recently Deleted keeps removed messages and attachments recoverable for a limited period
- Automatic retention can be set to a shorter period, but that changes future behavior for all conversations
A safe step-by-step plan
1. Check whether Messages uses iCloud
Before cleanup, understand that synced deletions may appear on every device signed into the same Apple Account.
2. Review one conversation
Open Messages, select a conversation, click the contact or group icon, and expand an attachment category such as Photos.
3. Start with large videos
Videos usually reclaim more space than images or documents. Preview each one and save an important copy before deletion.
4. Delete through Messages
Shift-click the attachments you reviewed, Control-click, and choose Delete. This keeps the app's database consistent.
5. Review Recently Deleted
Messages keeps deleted content in Recently Deleted for up to 30 days. Permanently removing it ends that recovery window.
What not to do
- Deleting Messages database files in Library
- Removing an entire conversation to eliminate one large video
- Forgetting that iCloud sync can propagate the deletion
How DiskSift can help
DiskSift is a local Mac storage analyzer. It shows the largest categories and files, lets you sort and reveal results, and separates conservative Safe to Delete recommendations from personal files that need your judgment. File names, paths, contents, and scan results stay on your Mac. Start with the free edition and review every action before moving anything to Trash.
Frequently asked questions
Can I keep a photo but remove it from Messages?
Save or export the attachment first, confirm the saved copy opens, and then delete the message attachment.
Why did space not return immediately?
The attachment may remain in Recently Deleted, and macOS may still be updating its storage calculation.