Rivet(s) on the vertical face, through or underneath the weatherstripping (aka P-seal), and some IMO poorly designed and quite annoying clips at the back. See page 20 of the instructions (for what they're worth, which ain't much)http://www.slosh.com/fierom...ructions%20T-Top.pdf
Assuming yours hasn't been dinked with, you can drill out the rivets and then CAREFULLY pry them up and forward, with a plastic prybar. Don't use metal like a screwdriver, or you'll chip the plastic on the trim. AMHIK. You'd have to replace the P-seal or at least work around it carefully to do so, however.
As for how to do it well/better, I don't know yet. I'm putting a donor car T-top setup onto my car, and I suspect I'll have to rework the mounting for those two pieces to my satisfaction. I hate to glue the thing down, but I'm thinking something flexible and/or expanding across the bottom back, and then screws or rivets on the front. Depends on what I end up doing for the P-seal area.
[This message has been edited by dremu (edited 06-28-2020).]