One decent solution when you're in a pinch:
Get a dollar bill or a piece of fairly strong paper (not glossy), put it between the tone hole and the pad, press the pad cup down, and slowly pull the bill or paper out. Repeat if necessary.
(I show this to students who have a $20 bill handy, then keep the money...when I can get away with it.)
The best way, especially for stubborn stickiness:
Moisten a bill or strong paper with lighter fluid and do the same thing. (Don't put so much fluid on that it'll drip onto your horn or into the tone holes.) Repeat if necessary.
The awful way that the Clarinet Police should arrest you for if you do it:
Dust the pad with talcum powder, baby powder, "pad cleaning paper", commercial "no-stick" powder, or anything similar - unless you want a gummy mess, dirty tone holes and pads, and crap all over your clarinet.
Over and out.