I made another account because I wanted to change the username, so I don't need this account anymore

I read  WEB-275

and a mod said the following
pokechu22 added a comment  22/Jul/18 8:23 PM  edited
There is no way for you to delete your account; however, we can get an admin to do it for you. Create a new WEB issue saying "delete my account", and then we can assign it to the appropriate person.

(this is a newer policy that wasn't in place when this issue was originally created)
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pokechu22 added a comment - 06/Nov/19 11:53 PM
When you create the issue, you want to set the project to "Mojang Web Services (WEB)". The issue type remains as bug.

thx.