You can delete them (for maxing needs)!
I have seen several posts about not being able to delete our poor sims for the purpose of maxing the need bars. If the purpose is for that, just activate the move_objects and make them sit on a chair, lay in bed, or something similar (pun intended?), and then delete the object itself. Then just click on the sim avatar as usual and they appear with their need bars refilled.
While it’s not equally straightforward, I find it good enough for the purpose at least.
Maybe this is already obvious to many of you, but this can hopefully help those of you looking to just maxing the needs. :)