I can't delete items in OS X (external startup drive)

[rodion15]

I have connected the system flash storage (SSD) on a macbook using target disk mode to another mac, because it can't be booted up (I suspect because it's almost full, only 1.2 GB free on a 500GB storage). Most data is movies on the iTunes folder. When I try to remove any of these movies or any folder in the iTunes folder, I get a message "can't be moved to trash because it can't be deleted". Why is this?

I set permissions to ignore permissions for the attached drive. Filevault is enabled, can this be the problem?: I've unlocked the volume by entering the password.

Also: when I try to disable filevault from disk utility (File > turn off encryption), it takes really long and I can't know if it's actually turning off encryption, I can't see any message that it's desencrypting.

 

[Leeky]

I strongly suspect the issue is because the alternative Mac doesn't have ownership or delete permissions for the files in question. It could also be because you need to be root to do it. The below assumes permissions are the issue.

Mount and authorise the disk, then open terminal and navigate to the movies folder.

e.g.
cd /Volumes/drive-location/
sudo chown -R $(whoami)

The same can also be achieved by the following:

cd /Volumes/drive-location/
sudo chown -R YourUser

If you want to give all permissions to everyone, you can do the following:

cd /Volumes/drive-location/
sudo chmod -R 777

That will recursively change the owner for every subfolder of the main videos folder on the Mac actually connected to the disk all the way through the entire videos folder.

You can then proceed with deleting the ones you don't want.

Once back in the original Mac, just run the above again to restore permissions to that Mac.