Our Delta tub spout leaks when we use the shower. I have remove the spout and was going to replace it with a universal spout. However, when I unscrewed the spout I noticed a large, threaded copper sleeve remained attached to the copper water pipe. I can't seem to remove or twist the copper sleeve. How do I remove the copper sleeve? Is it sweated to the copper water pipe?

If you have a three knob showere valve then the problen's not in the spout. DO NOT remove the threaded male adapter on the end of the copper stubout, it's soldered on. It's there to connect to a front end threaded spout, (see image).
Let me know if your Delta shower valve's a three knob valve? Regards, tom