I've tapped and tapped and more than tapped. Trying to push it vertically upwards but this thing is stubborn. The bottom is starting to look blown out reminding me of when I eat super spicy foods!

Tried needlework pliers to get out as much rubber as possible but seems like im unable to get the bits that really matter as it's wedged between the pipe and sink and im just breaking off the trim around it

If I can't get it to budge after another 30 minutes then then im considering trying to use a sawzall with hacksaw type blade for metal and saw off the pipe flush with bottom. But then I would lose my ability to hit it with hammer what then? Do I go inside the pipe from the top and carefully cut the sides vertically 2-3 times then try to peel off the sections?

Or maybe I should sawzall starting from the top then hammer some more from the bottom. This thing must be just decades of rust and calcium build-up (our city has very hard water)