i just use the tank/pump to pop the fill valve then open the bleed VERY slowly and let it trickle out ... maybe there is a tool for it, however i never bothered looking for one.while it IS slow, it does work on mine
If you don’t have a degas tool, I have unscrew the air tube gauge until I hear a hissing sound bleeds the cylinder fast
If I was going to do the gauge method I'd shoot it down to less then 1000psi, that would make it a little safer and probably less stress on the gauge threads.
Shoot it out!