Hi, has anyone had to change a sink gate that was soldered into a wall and had to turn the compression fit. Out of the way of a pop-up rod after changing the sink. The chrome pipe can't be heated enough to unsweat it from the copper feed.

"The chrome pipe can't be heated enough to unsweat it from the copper feed."
Sure it can. You just have to evacuate all the water out of the pipes first.
Liquid in pipes act as a heat sink so the pipes won't get hot enough to melt solder.
What you have soldered to the copper stubout is the chrome trap tail. Since chrome can't be soldered we take a file and file off the chrome until we reach the brass pipe stock underneath. Then we can solder the two together.
Get all the water out of the pipes and keep running your torch all the way around the solder joint, meanwhile pulling on it until it loosens enough to release it. Map gas will give you a hotter flame then propane although propane will do the job just as well. It will just take a little longer. Good luck, Tom