So the little lead end on the Bowden cable is stuck in the lever? I'd disassemble the lever assembly and see if I could grab the protruding (the end without the lead end) end of the cable very close to the lever and push. If there is no cable sticking out, a pin punch might push it out. Or even a paper clip end. Or put the lever in a drill press vise and drill a little 1mm hole in the lead thingie and see if you can get a screw into it to pull out. Or use a drill that is the diameter of the plug.

Be advised the inside the plug is ball of bent up wire.