There is no appropriate convention to yell something at someone holding an elevator door to tell them to not hold the elevator (Sorry, for my British readers, I mean to not halt the lift). There are plenty of conventions for the opposite. If I'm running late and I see someone I know get into an elevator right as the doors are closing I might yell "hold the elevator", and they will grudgingly stick out a hand or at least feign some sort of gesture towards the <> buttons, or maybe they'll at least politely pretend not to hear you.
However, I have the opposite problem, in which I find people on my floor are irritatingly and unnecessarily polite. On our floor, the men's room is right next to the elevator (Sorry, for my British readers, I mean the Gents' loo is spot ajax the lift (Sorry, for my LA readers, I mean the elevator is Beverly-Hills-Adjacent)). Frequently, someone will get into the elevator and see me entering the shared hallway, and they will politely hold a hand out to keep the door open, only to have me walk right past them and quite literally piss all over their kind gesture. Unlike yelling "Hold the elevator!", I don't feel comfortable yelling "Nope, dropping a deuce!" in a work environment.
This is what it's like inside my head. Now you know why I don't blog more.