Can't disable page creation

I'm using Sharepoint online.

I disabled in admin page creation few days ago. User has restricted permissions, but they are still able to create pages on my subsite. Yes, the permissions are correct and unique. 

Is there a way to do it via powershell ? I know i can disable it for specific sites according to this link,

However, it doesn't work, always throws an error, and besides it's unchecked at the admin center either way.