How do you make household sims npc

Minai

My sim is in a university housing but I dont want to control the other two sims that came with the game.
How do I make them just plain roomates?

SimmyFroggy

You can't switch them to NPCs but you can move them out of your household and they might show up in the dorms as roommates. From what I've seen though, it's not very likely that they will.