Legal Question in Legal Ethics in Pennsylvania

Re: need to find out what form is needed to fire a lawyer

No such thing as a "form" for this (unless your retainer agreement with the lawyer had some provisions about the method for termination).

You just write a letter, no magic words needed, just say that you are terminating the representation, please return my file.

It's a good idea to consult a new lawyer first, to get advice on the ramifications, particularly if the first lawyer has a written fee agreement.