If you then, say, download some large program and your internal hard drive plummets to below 10% (or less than 5GB of internal storage), Time Machine will delete all local snapshots except the most recent. If everything is working correctly, Time Machine will automatically delete the oldest snapshot backups as soon as your internal hard drive has less than 20% of storage space left. Remember that when you move a file to the Bin, its storage space won't become available until you empty the Bin.First, let me preface this by saying that you shouldn't worry about those backups and the space they are taking up. Then expand them when you need to use them again. If you don't want to delete certain files, you may be able to save space by compressing them. Check the Users folder on Macintosh HD for any shared files that you no longer need to share.If your Mac is set up for multiple users, delete users who no longer need access to your Mac. Or ask them to follow the steps in this article after logging in to their user account. Also check the Users folder on Macintosh HD for any undeleted data belonging to deleted users.If you use your Mac to back up your iPhone or iPad, you can delete old backups.Also choose Mailbox > Erase Deleted Items.

If you use the Mail app for your email, choose Mailbox > Erase Junk Mail from the menu bar in Mail.Delete files in your Downloads folder. Open this folder from the Dock or by choosing Go > Downloads from the menu bar in the Finder.

Delete music, films, podcasts or other media, especially if it's media that you can stream or download again as needed.

You can also delete files that you no longer need. If you have another storage device, such as an external drive connected to your Mac, you can move files to that device. Media files, such as photos and videos, can use a lot of storage space, so you can take steps such as these:

Clean up mac hard drive space