They came from the supplier with the adhesive already on them and once you set in place it was not a fun proposition to try and remove it.
This brings up an interesting question: since you were on the assembly line, you'd know exactly the placement and size of the adhesive strip. Assuming you first peeled off a protective backing strip, was the adhesive masked along the edges or did it cover the entire surface?
Just doing a quick (and gentle) test with a screwdriver to see what kind of leverage/pressure it would take, settled it for me. I don't recommend trying this.
And something else came to mind....isopropyl alcohol dripping down the backside of the lens...across the adhesive and the underlying silkscreened paint job. This can't be good. I suspect that even if the lens was cleanly removed, that there will be some sort of irreparable damage to the backside finish that cleaning won't solve.