How can I change my iTunes home library for my iPhone?

I initially synced my iPhone with my desktop computer's iTunes, and thus that becomes its "home library", and it won't let me sync with any other computer (which is understandable). However, what if I want to change the "home library"? Like if I buy a laptop, and then I want to only sync with my new laptop (I don't want to sync with my old computer anymore). I'm hoping there is an easy way to do this without deleting any data. Thanks!