Yes I have a 99 yukon and cannot figure out how to pull off the retaining clip from the booster to the brake pedal. Its like a circle with little prongs aroud a metal bolt??? please help

sounds like a simple clip over a rod. if it is the one i'm thinking of take a small flat bladed screwdriver slip it under the top of the clip, the part that is over the rod end, then turn screwdriver slighlty and one end of the clip that goes over the rod will pick up over the rod. then just push clip so that the part that came up goes over the end of the rod. the clip should pop right off
if it looks like a little star its a push nut and you just have to pry it off from under the bottom of the clip. this type is not made to be taken off and you will need to get a new one available at any parts store