Lower it down to the build plate and turn on the plate heater as high as it’ll go, too. That’ll speed up how quick the plastic softens. Get it warm enough and it ought to just peel right off.
The few times this has happened to me over the years, I used my fingers rather than pliers. Yeah, you risk getting burned, but you reduce the risk that you’ll “over tweak” the extruder and damage it or the nozzle with the additional leverage pliers provide… Get any last little bit left by wiping down with a thick folded up piece of paper towel after the big chunk’s removed.