is it a shift lever?
put into reverse, roll a few inches, neutral, try to disengage.. failed? put it in drive and move forward a few inches, neutral, disengage.. failed? put it in reverse, while rolling, put it in neutral, attempt to disengage.. failed? take the scenic route home.
sometimes you gotta struggle with it.. mine always eventually disengages. sounds like you got some binding, check your tire pressure and make sure all of them are at the same PSI, all have roughly the same amount of tread, and all tires match. a mismatched tire will cause binding in the driveline, making shifting the transfer case a pain in the ass, if not impossible.