1998 Chevy Silverado Removing vacuum booster

We are trying to remove the vacuum booster to replace it. We can't figure out how to disconnect the brake pedal from the booster arm inside the cab of the truck.

There is a little black clip on the right end of the shaft, but we can't figure out how to get that clip out. It is difficult to get to that clip with the mounting brackets and steering column right there too.

Is that even the right approach? Is there a special tool required to do this?

Thanks
EJ