need help removing a window 2002 impala

can anyone tell me how to remove the widow and power window track from a rear door of a 2002 impala? I have removed all of the interior trim and rubber trim from around the window. There is a "cap" at the top of the door frame held on with rivets. Does that have to be removed? I need to pull the glass and slide/motor. The cable system appears to have broken and the glass is stuck in the down position. Please respond ASAP, dark clouds on the horizon!