Delete permissions from site with powershell

Hello,

I know how to delete permissions from lists and doclibs. Simply i can use the breakroleinheritance, and i can remove every user. But i couldn't find a way to do this with a site.

Lets say the $site = http://spteszt/spaces/thisisit

$site don't have inheritance method. (or i just don't know how to use it)

So how can i delete every permission on a site? Not on the lists, not on the doclibs, bot on the site itself?

I Hate Mondays