[Ron Wood]

Without pictures, it sounds like you are talking about the sear bar spring. It needs to be removed to take out the sear bar. Lift up on the front of the spring by inserting a small screwdriver under the curved forward end. Push the spring forward and it will slide out of the frame. The sear bar can then be lifted out of the frame.
To re-assemble, put the sear bar back in the frame, place the spring on top of the bar and press down and back to slide the spring back into the groove in the frame.