Hey Becky,
Are you looking to just remove them from the flow or add another Program Status value?
If the former, you can use the "Remove from Flow" flow step based on any criteria you want.
If the latter, then you will need to go to the Admin tab, click on Tags on the left side of the screen, expand the Channel tab, and double click on the Webinar tag. Within here, you can add statuses, but make sure it is in the right order because that does matter. Statuses cannot go backwards.
Hope that helps!