A person can do anything they want to do. You have to deal with the consequences, though. If you believe your lawyer is not adequately representing you, you have every legal right to terminate the relationship.
You can fire an attorney at any time. You will still owe him money for the work that he has done for you, however. If you paid a retainer, he can keep the amount for the fees that he has earned, but must refund the rest.
Yes you can definitely fire your attorney. If you have genuine reasons to or maybe not satisfied with his/her work you can hire a new attorney. Why should you keep some attorney if you are not happy with the work.