src.overlays-=/obj/certainoverlay
I set this to the login code and I know for a fact that it's removing the overlay but I think it might be that the overlay is blended in with the icon. One way I can remove the overlay is by removing all overlays from the player but I want to know if it's possible just to remove this one overlay.
All I did to add the overlay in the first place is:
src.overlays+=new/obj/certainoverlay
> src.overlays+=new/obj/certainoverlay
Nope. Can't do that. Once you add an obj onto a player and logout, it's done. I personally only like adding ".dmi" to character's overlays anyhow. You should have some way of tracking what the player has equipped, should you not?