I have a bad AC compressor clutch on my 03 chevy blazer. I need to know what size deep well do I need to remove the bolt holding the pulley... can't see it and I have no idea what size it is, and is there anything else that I need to know to remove the pulley

It most likely does not have A nut and is just A press fit. You will need A clutch pulley puller/installer to remove the drive plate then snap ring pliers to remove the pulley/bearing.