Sadly there is no OPTION to just fully disable the sidebar feature. But there are ways to avoid it your entire time on the forum. The first step is to navigate to your profile
Preferences -> Interface -> Default Home Page -> Categories
This will return the default homepage of the forum to its old category showing page.
Then you simply click the hamburger menu on the top left of the forum to hide the sidebar. Then you operate the forum just as before by clicking the logo whenever you want to return to the homepage, or previous page.
For mobile, its the same thing, you never touch the hamburger menu basically.
The only thing that people would notice is the change in the way notifications are showed as instead of a horizontal button list it is now vertical.
Thanks,
Headless.
