Normal razor blades will probably scratch the glass so be careful. De-solv it sounds like the best option as its easy to get. If you are able to spray the adhesive and then cover it again, this will give the best result of breaking down the glues.
Tinters use a softer blade and soapy water for glass with out heater lines. There is some thing else but the name avoids me atm.
Done this many times on customers cars when I worked along side a tinter.