How to be permanently banned from dota 2?

How about some self control?

Impossible.

You can always roll up a new account and start playing again.

install game, right click, set categories, hide this game in my library.
When you try to find the game... say to yourself, this game is hidden for a purpose... to keep my self in control.

add the dota.exe to your antivirus so it gets deleted as soon as it gets downloaded :p

addicted to dota 2. yep, 2015 was a great year