What would happen (other than pain) if I pull out the large nerve that came from underneath a partial upper wisdom tooth? (it is sitting on my gums)

Please see a dentist. Firstly, there is no "large nerve" for you to pull out... the nerves are embedded in you bone and gum tissue, which you cannot visualize or dissect. Secondly, you are attempting to perform dentistry, something that takes everyone else years of education and experience to master. Your best any only option is to be seen by a local dentist.. make the call.
See Dentist. There are many problems that could happen You should see Dentist.
See a dentist. i am not sure what you are referring to. There is no nerve that is just sitting on top of the tissues. Get this area checked by a dentist. Find out what is going on.