Loose tooth with new tooth growing behind it. should i just yank it off?

That depends: Have your dentist take a look at it and see how far along the primary tooth is resorbed before you try to "yank it off". You might need help. Sometimes part of the primary root doesn't get resorbed, and you could break it off leaving it inside, which isn't a good thing to do.

Maybe.: I am assuming you are not speaking of your own tooth as a 44 year old should not have loose teeth if healthy. This is normal for children under 13 years of age and the loose tooth can be removed at home if the child is cooperative. If you are speaking of yourself you should see a dentist.