Dave Liquorice expressed precisely :
I suspect scraping off is going to be the only option, they are far
to soft and gunky to peel off. Scraping will leave a residue on the
glass, any ideas of a solvent or cleaning agent? Google is not very
forth coming.

Try WD40, to prevent it re-sticking as you scrape.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk