Leaking Delta bathrub spout

[bsptpc]

Hello and thanks in advance for any assistance offered.

I have a leaking bathtub spout. It's a whirlpool type tub. It has a spout and two separate knobs for hot and cold. The spout and knobs are on top of the tub...not in the walls of the tub.

It is leaking hot water.

I removed the hot water knob....and there looks to be a hard pipe stem with a plastic part inset into it.

Any idea how to remove the plastic part?

Thanks in advance,
Chris