A piece of my gum is hanging off in the back of my mouth where my wisdom tooth is coming in. Should I pull it off?

Absolutely not. Sometimes as teeth erupt the gum tissue that was over the tooth resorbs unevenly. If it is bothering you, or if it does not resolve in two weeks, see your Dentist. Pulling on it can cause problems if it doesn't release the way you picture it coming off.
Hanging gum. I don't suggest you do that as it might make things worse and is not addressing the cause of the problem. Please see your own dentist to see what's going on and how best to treat.