Unable to move Computer account to new ou after moving it once
Not knowing your OU structure I would advise you to check these things:
- The "Applies to" section of your allow ACEs. It should be "This folder, subfolders and files"
- Check if the has "Protect from accidental deletion" checked in Object tab of the computer account. This checkbox adds explicit DENY ACEs in object's ACL which take precedence.
Also, IIRC the user that moves the object should have "delete" permission in the current OU.