Well, when you create the event that gives the choice to refuse entrance to the room, set the choices, and when the response is the choice to refuse, set a switch or a variable. Then, make sure that the event page is only triggered if the switch is set off. Make another pages that is triggered when the switch is on. When the switch is on, for example, a game message may appear that reads, "You have refused to enter the room".
Later, you can use another event somewhere else in the logic of your game to turn the switch off again. That way, when you go back, the event page that requires the switch off is triggered, again giving you the choice to enter the room. You can use variables instead of a switch to make different outcomes too.