You can squeeze the cup and crush it in a vise to make it easier to take out if you don't plan on using it again. If not...yeah. Just hit it with a chisel/flathead screwdriver around the edges and on the inside.
I've had to do this at work and it honestly sucks ass.
Either take it to a bike shop and have them do it, or use a old razor t tube and put it in at a angel, hammer away