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.