How to get unbanned from minecraft server?

Uninstall, download approximately 2.34kg worth of memes and re install Minecraft, should get you unbanned and then stop hacking

YOU DON'T!

You know what you did & the staff imposed the appropriate actions for your undesirable action. The best you can do is just don't attempt the circumvent the ban (as all you're doing is escalating the issue, which will likely result in your alternate accounts getting banned & the staff imposing an IP ban or even an IP-range ban against you) & just move on.

You could contact the staff outside the game & request a ban appeal, but considering the severity of your actions… You'll probably want to give them some time to "cool down" (at week at the bare minimum) & be honest & sincere with your request (expect to apologize to the person you grieved). HOWEVER, it's probably better for everybody if you just move on as the staff may have considered your actions irreconcilable & may not repeal the ban.

Since I don't know the moderating staff of the server in question, I can't assist you in getting your ban repealed & such actions would make me hesitant in directly assisting you… It's ultimately up to you on how you proceed. I just hope this sheds some light on the subject to better guide you.