from the scrap bikes i collect that had jammed chains between the BB and crank.. i always had to remove the crank first (using a crank extractor tool) to free it.

one of the reasons why some people give away their bikes here, they come across a problem and don't want to deal with it. my gain!

for me it's an easy fix, then adjust the derailluer so it won't happen again. put the bike up for sale


OP, once you sort this out, i recommend to check the rear derailluer, that could be out of adjustment too