As far as i know with the OEM korea bars ,Β they tend to spot weld them inside
however , here is an ideaΒ (please be creative and becareful) . Get a “Hole Saw” attachment for Steel Cutting , on your drill, then measure the hole inside your handble bar, find a hole saw that fits inside.
Then use the drill attachment.Β What will happen as it will make a deep circular cut until it consumes the insert.Β Then it should come out.
This is just an idea,Β you may feel free to use a better idea than myself π