Fixing sagging headliner

Anyone know how to take the plastic molding off on the sides of the headliner there's no visable screws does it just pop right off? My headliner is sagging on the right side oF my 87' ciera and I want to fix it.

Thanks

Yes they pop off you may have to start at the A pillar and work back. I have seen people use spray adhesive on the sides when putting it back up. Seems to work for them.