changing coolant 97 K1500 350

I was going to replace my coolant today but I'm having trouble draining the radiator. There is a little white plug[?] with a tee type handle that I can't reach on or near the bottom of the radiator on the drivers side . I assume that's for draining the radiator . I ground a slot in a socket and could turn it about a 1/8 of a turn and nothing happened and I didn't want to force it. I saw a plug in the drivers side of the motor for drainging but didn't pull it out cause I couldn't do the radiator, I saw what I think is the temp. sensor on the other side of the block and I guess I could pull that for draining the other side of the block but what about the rad? pull the bottom hose? Thanks, Tom