Tricky demo of fence post abutting concrete wall

Hi! Completely new to outdoor projects and demolition. Pardon my ignorance.

Currently demo-ing some rotted fence posts. One of them abuts our concrete retaining wall. It seems like the concrete from the fence post is melded together with the concrete wall.

Any ideas on how I could completely demo the post OR at least get more of it out without causing damage to the retaining wall.

So far I've used a large crowbar and sledgehammer to do the work you see in the attachments.

I'm not planning on replacing it with a new fence post, just planting some bushes; however, I'd prefer to remove as much of it as possible without messing up the (already messed up) concrete retaining wall.