Kitchen torch is almost the right idea, what you want is a hot air gun of some kind. I have a hot-air rework station, which cost me like $45 including sales tax, and lets me set the temperature of the air coming out. Get the nozzle off and get ready to clean out the entire hot end, which for the nozzle means getting it clamped onto some sort of holder (pliers, even, but preferably better) and heating it up with the hot-air gun until you get the filament melting. Then start clearing it out from the wider end using, say, a bamboo skewer, which I find effective and non-scarrning to the nozzles.

It’ll take some futzing around, but you’ll get there.