I wrape small wire around them and under the head and gently pull them off..You could pry with a small screw driver work around instead of one area..there plastic and damage easy!!
Home Cheapo also sell some caps that are decent..You can buff them up to look better..
harley shops also sell chrome caps..I have them on every hole on my bikes..
Eventually lost all four of mine after lowering it as well. Apparently they're one time use or we don't have the ninja secrets of removal and installation.
I didn't even know they were caps when I swapped my triple tree swapping it out an tightening them back up with out taking off the caps was quite a workout
And I was cursing Suzuki's good name for making these weird ars bolts with no kind of head to grab on