How to get the fixed part of a bar-end shifter out of the handlebar when it is stuck?
I suspect vice grips or plumbers pliers/sliding lockjaw pliers will do the required.

Since the fitment is not turning in place, there's a good chance that the shifter is stuck to the inside of the bars by corrosion, either rust or aluminium oxide.  I note the upright nature of these bars may encourage salty sweat to enter and weep down into the bars.

This appears to be the left shifter, for the front chainring, so is likely to be used less and have more opportunity to settle.  More-frequent adjustment of the rear/right shifter could have helped keep it loose.

Suggested method of attack:


Start by blasting the seam with a penetrating oil.  Anything that can wick its way in will help.
Then try to spin the fitting in the bar - you might need leverage from a stout screwdriver through the mounting hole, or the big pliers around the face.  Use masking tape or a thick old rag to minimise damage.  Also be mindful of damaging the part you want to reuse.
if you can get the handlebar restrained, try feeding a light rope or wire through that hole and have an assistant put steady pressure on the end (ie, in line with the tube).  Use your pliers to wiggle the fitting back and forth.


A last resort could be to apply a hot hairdryer exhaust to the outside of the bars - in theory the aluminium will heat up faster and expand a bit.  The risks are to anything that is not metal - rubbers really don't like heat, and its also possible to set those oils earlier smoking.  Plus a hot metal handlebar is a burn risk.  Don't use flame - that's too aggressive.

Take your time on this - there's no hurry.  It could be that a bit of patience  will work best.