Maybe a very easy answer to an even more easier question. I've transferred my "old" MacBook to my girlfriend, without erasing the entire disk but only the necessary parts of it. As I worked on this Mac with a Developer profile, the OS updates (El Capitan) are still pushed on that track. To update, she can only use my Apple ID as her ID does not have the rights to do this. Is it possible to change this, without a clean install of the OS? If yes, how? Any help is very welcome!