personal attacks & verbal abuse/ how to block?

without immediately doxxing this user, id like to make clear they already have a zero reputation. but after personal attacks/verbal abuse on replies to my posts i would like to get some help...

i have his info and everything, but i would really also like to BLOCK the account if thats possible....
...i've also been struggling to even find where i can downvote their reputation- could this be because it is already at 0? again i have the info of the account i'm just not looking to make a big deal. i wuld just love some help if i can block the account and move on