Try a cotton swab soaked in nail polish remover, too bad glue has had
time to set. If all else fails, glue another mounting plate to
windshield, keep old one in place as a reminder.
" Fixed Fortifications are a tribute to the stupidity of
Modern Man " Gen. Patton
Too bad the mirror plate doesn't have markings, as to Top + Bottom
and which side glues to glass. I've made a similar mistake, mounted the
thing upside down, wound up mounting mirror upside down, and rotating it
to put day night lever where it belongs.