is there a way to make a forum thread like a sticky so that people fill out for instance their raiding schedule for a week and at the end of the week it clears by it self.
Not that I know of. However there is the new Raid Availability Tracker that should show up in the Logged in As section. It doesn't reset after a week but is a place that is intended to allow people to fill in their schedules for a week. Anyone can then access the tracker and see who is available on certain days of the week and what times.