There was a program on TV about the intelligence of crows. Using face masks, one "face" would walk along, not threatening the crows in any way. A different "face" would do something scary/mean and the next time that one walked by, the crows would send the alarm call. They do have incredible memories and can tell us apart.
This crow seems to be quite upset that you disrupted his meal. S/he may have babies to feed and is now defending its territory as well as food. They can get quite aggressive during breeding season.
Wearing a hat when you go out into that area will protect you. They tend to swoop by and intimidate but not do much real harm. They just want you to go away.
I can't think of a safe/legal way for you to kill the bird. If you try poison, some other animal may pick it up and die. Then you're in trouble. In time the crow will get over it, move on with the group and not pester you any more.