for the 21 endings with no save feature allowed do you have to let the narrator talk all the way through for the endings where you restart the game at? Like the broom closet ending? Do you wait for the narrator to stop all his talking then reset or just open the door go inside and reset?

You reset wherever time is stopped in the individual ending runs, unless it's one of the ones that resets automatically.

I can confirm, that is how it works.

On Broom Closet ending do you have to reset or can you continue to another ending upon exiting the closet? I.e. In a 21 ending no save run could I stop by the broom closet on the way to freedom ending as a casual player might or do the rules require a reset once I'm in the closet? Similar question for Whiteboard.

EDIT: Bothered to actually read the rules. I redact my earlier question.