Yes . you can change your facebook user ID. That doesn't mean user name.
STEPS:-
1) If you want to change your user if .Then at first Log in to your Facebook account from a Computer.
2) Then go to "profile".
3) Next click on "about".
4) Now click on "Basic &contact info".
5) Now just click on "edit " just right of of your Facebook use .I'd.
6) Next change it to your own preferable name .
7) Now click on "save". that's al...
