I've used my Time Machine drive to back up my main machine, and also a friend's mac. Her machine is now being backed up on another Time Machine drive, and she'd like me to delete her backup.

I'm familiar with the (perhaps obscure) way to delete a particular time machine backup, or how to delete all backups of a particular file, but I have no idea how to delete another machine's backup.

If I had access to her machine, I'd plug in the drive and delete the entire backup of her drives using time machine on her computer. Whether or not it is reasonable to have to do this is irrelevant, I guess, because that machine isn't available to me. :)

Please nobody suggest I drag her backup to the trash. I did that once and the trash never finished emptying.

Any ideas?

  • I dragged the backup folder of one of my old machines and, like you wrote, I cannot empty the trash. Also I cannot drag it back because there is an error: "The operation can’t be completed because backup items can’t be modified." So how did you get rid of that folder? – puri Mar 24 '11 at 5:58

You can use the tmutil tool to delete backups one by one.

sudo tmutil delete /Volumes/drive_name/Backups.backupdb/mac_name/YYYY-MM-DD-hhmmss

If you are sure you have selected the correct name, you can delete all backups from that one Mac by not passing in the time and letting it delete the entire folder:

sudo tmutil delete /Volumes/drive_name/Backups.backupdb/mac_name

The sudo command needs your password (and it won't echo to the screen, so just type it and pause to be sure you're dating the correct files before pressing enter).

  • The other Mac's name doesn't appear in the Backups.backupdb folder for me (on 10.11.3). – Sam Brightman Mar 30 '16 at 5:40
  • @SamBrightman Is it possible the drive was full and old backups got pruned? It's not usual to have all backups deleted - the system normally leaves one intact in the worst case. Maybe start a new question if you'd like help making sure it's not a permissions issue on the drive or failing drive? – bmike Mar 30 '16 at 13:12
  • This command doesn't work (anymore?) to delete all backups for a machine, you can only remove individual backups with it in Catalina. Trying it for a machine results in Invalid deletion target (error 22). – mgol Mar 4 at 22:19

It should be something along the lines of

$ sudo rm -rf /Volumes/BackupVolume/Backups.backupdb/machinename
  • 1
    I seem to remember trying this "last time" and the command hung for many hours. I ended up just re-formatting the drive, but I don't want to do that in this case... – aaaidan Mar 9 '11 at 4:30
  • It will take a while if there are many backups, since it's all individual files and not archives. Wait it out. I just did this on an ex-Time Machine drive (having migrated the backup to a larger drive) and it is slow but it will finish. – geekosaur Mar 9 '11 at 5:16
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    This won't work since the filesystem protects the Backups.backupdb even from the root user asking to delete files. – bmike Jul 5 '12 at 20:06
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    rm -rf doesn't work, even with sudo (fs denies permissions) this is the only way to go:<br> sudo tmutil delete [path to machine name] **Example:**<br> sudo tmutil delete /Volumes/BackupDisk/Backups.backupdb/oldmachine – Magnus Rifkin Oct 10 '15 at 3:16
  • tmutil delete for a machine folder also doesn't work: Invalid deletion target (error 22). It only works for individual backups on Catalina. – mgol Mar 4 at 22:20

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