Drive Belt AC question

My AC compressor is broken and looks like it will need replaced. There are two plates on the front that I believe are supposed to spin with the drive belt but they don't, they actually make a horrific grinding sound when I turn the AC on. Anyway, I know I need to depressurize the system before I started disassembling any parts, Is this something I can do myself or will I need to take it to a shop?
Thanks...

you can just replace the ac compressor clutch instead of the whole unit... that is unless the compressor housing is shot as well, and expelled refrigerant

http://images.channeladvisor.com/Sell/SSProfiles/43000297/Images/9/1521291ACM.jpg

that black thing that goes on your serpentine belt... there's tools that you can rent to remove it from the compressor

that electrical plug goes to a solenoid & that is locks the clutches to the drive pulley, "compressing" the refrigerant