I am having problem getting the "horseshoe"washer off the pipe underneath the sink to be able to remove the faucet. Any ideas on how to loosen this washer to slide off. I have tried WD40.

Most Grohe horseshoe washers are held on by a retaining stud and nut. Did you remove that? Then, have someone wiggle and pull the faucet up. Should come out.

What model number. With many Grohe kitchen faucets, the spout pulls off (pull straight up), That allows you to unscrew the base on top, and remove the body of the faucet from underneath. Call 1- (800) 444-7643 for technical assistance.

Yeah, as Hkstroud said, most likely you'll need to disconnect the pull out spray and drop the hose down through the valve and then simply pull up on the spout to gain access to a toothed stem that can usually be loosened with pliers or a crescent wrench.

Good luck!

Mark