So my friend was visiting this weekend and he saw how many hours i was into New Vegas. So he thought it would be nice for me to 'be a pirate' and 'gave' me the dlc's. So now ingame i got the starting quests and a level cap of 40.

How do i get rid of it?

Cross its name out of your address book and don't answer any of its calls. If it comes knocking hide behind the sofa and don't answer the door.

On your PC, delete the DLC ESM files.