Should I kill this guy? (NSFW.)

I’m almost 40 years old, now. There’s a new guy in my neighborhood. I think he’s just passing through. He’s probably homeless, and desperate. But he’s mean mugged me multiple times, and seems intent on harming me.
He looks like he’s in his 20“s, but he doesn’t seem to understand my capacity to stomp a puddle, in his ass.
I have multiple training in MMA, and I’m not having a good time lately.
I’ve seen him a few times, and he seems ready to throw down. I’m NOT afraid of him, and I don’t think he knows how badly I can hurt him. He is probably 50 lbs lighter than me, and I don’t know why he doesn’t like me. But he thinks that he can like “bully” me.
I’m not sure what his problem is, but he’s barking up the wrong tree.
The next time I see him, I may engage him. Which won’t go well for him. I’ve been in hundreds of fights, and I have reservations killing him. I think he’s just young, and stupid.
But I won’t let him disrespect me either. I’m not 315 lbs anymore, but I’m still about 250 lbs. And I know how to kill a man. (Came close a few times. ) I’m not afraid of his knife, and I even if he cuts me, I am confident that I can kill him. (I’ve fought people with knives before.)
But….Like I said, I think he’s young (20ish.)
He’s been hanging around my neighborhood, for a few weeks. But, he apparently thinks he can “run shit.”
I see him every few days, and he mean mugs me, and talks shit.
I have already talked to local Police. They say to avoid him.

FUCK that. This is my neighborhood, not HIS.

I walk a lot, to get to where I’m going. I’m growing sick of seeing him.

Should I be the wiser man, or should I stomp a puddle in his ass, and get it over with?

I have a history of being a LEO, and I think things would go my way in court. If/when I kill him….

He’s tried to confront me multiple times, in the middle of the night. To this point, I have ignored him. But. We will have to deal with who’s neighborhood this is, eventually.

Should I avoid him , or do what I think should be done?