I have a 46 chevy pickup and the clutch is rusted to the flywheel How can I free it up.
Try soaking the thing in a bucket of antifreeze for several days. It should dissolve the rust buildup eventually and won't harm the flywheel 
Years ago I made the mistake of storing my 1940 Buick in the basement of an old clinic that was damp. When I tried to start the car in the spring I found the clutch to be stuck. I don't know where I got this method, but it worked.  I put the transmission in neutral and started the engine and ran it a bit to warm it up. I then shut it off, shifted to first gear, depressed the clutch and tried to start it. The Buick has a starter switch connected to the throttle linkage so I possibly started with the hand throttle, otherwise hold the brake down with your heel as you depress the gas. As the engine tried to start the  clutch popped loose.  This method worked more than once as I was too dumb to get the car out of the damp environment.
Richard Owl-Mirror
I realize this post is a bit old but, maybe this will help someone in the future. It's not my advice but, seeing as I am learning to be a DIY restorer, I came across this video on YouTube. Hope it help someone. - Remove Rust from Metal and Panels the Easy Way: Video 1
via @YouTube
I've been told, the only stupid question is the one not asked.

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