I have a leaky frost free. I need to take the head off but the entire unit turns when I try. I’m not strong enough to hold the pipe in place with one wrench while turning the head with another. Any suggestions on how to immobilize the pipe? Concrete seems like a bad idea. Maybe bury a 4x4 behind it and clamp the pipe? If I have to digit the entire unit I’m gonna be sad.
Thanks!

They can be on there tight. First, raise the handle to the highest point. Then disassemble the handle and linkage on the head that raises and lowers the stem. Once it’s removed, you’ll need two wrenches- one on the column and one at the base of the head (hex) to turn it off. I always heat the hex portion of the head to help loosen the metal before I do any wrenching. Good luck.

"the entire unit turns when I try"

you may have caused an additional problem inside where it connects to the water piping.
Best to go inspect the point of connection for leaks or damage.

I agree, you most likely broke the seal where the frost-free faucet was connected to the inside pipe. This will probably have to be redone with new Teflon tape or pipe sealant. You have to have two wrenches one to stabilize the faucet body and another wrench to loosen the bonnet not to get the damn out to replace the washer

I have the impression that this is an outdoor "yard hydrant" into the ground.

You are correct. I meant “Yard Hydrant.” I probably will have to dig the whole thing out and check the connection as you all suggest. That hurts. It’s 4 feet in the ground.
I tried 2 wrenches, but still couldn’t budge it. I have a propane torch, never used it like that. How long do you apply the heat?
Thanks for your help folks!!

how long you apply heat depends on how big the torch head is.
get the fitting good and hot.