Do not yank curtain off. The snap side embedded in the plastic headliner can be yanked out (the one pulled out of mine was just a screw in rather than a rivet; don't remember, but I think Airstream replaced with a riveted or one with a backing).
Someone else posted about keeping a thumb on top of the snap curtain side and using a finger slipped under the curtain to pry off each snap. No yanking.
There was at least one Westy which did not have the gray circular trim piece around the snap part embedded in the plastic headliner. The trim piece make for a more finished look and a more attractive dimple in your forehead?
For quick cover, I use the Walmart available Super Jumbo sunshades in two pieces. Easier to handle than a one piece, but still have to use a figure 8 maneuver to fold up.
Note: Don't remember who, but a Westy owner added some more snaps behind the front seats to hang the same windshield curtain. Made a quick half curtain for some privacy without adding a full curtain rod/track and a separate curtain.