Unlink iPhone from a computer and switch to another I've just run into quite a big problem. I bought an iPhone, and the person who had bought it from the store for me had, being a nice person, helped me charge it. 

Unfortunately, this meant that the iPhone is now synced to the PC that she has and not my MacBook Pro. 

Is there any way to change this?

Thanks in advance.
If any apps or music came preloaded on the phone, make sure you have copies in your iTunes library before starting.

Plug in the iPhone and start syncing as you normally would.  iTunes will ask whether you'd like to wipe the phone and sync with this computer instead.  Just say yes.