How do I unsync my iPad from one itunes and sync it to another?

I recently purchased an iPad. My Parents both own iPads that are synced together and when I went to plug my in to "register it" it automatically synced with theirs and I do not want that. I would normally sync it to my laptop instead either of theirs but my laptop is not available right now. My laptop has its own itunes and everything but now my iPad is synyed to their itunes. Is their anyway I can unsync mine from theirs? I already tried switching apple ids but that didn't make a difference. Thank you.