Since my uncategorized topics page is still accessible by URL by ordinary users (it’s now a totally blank page), if I could just remove the Uncategorized link from the hamburger menu I wouldn’t have random users clicking there and getting that blank page. So far the CSS solutions I’ve found have not worked. I’d be fine with removing ALL the category links from the hamburger menu, actually. Obviously, I’ve checked this both from a staff and ordinary user account, and have unchecked the “permit uncategorized posts” setting. Thanks!
AI-generated summary
A user, L30110, wants to remove the “Uncategorized” link from the hamburger menu since the corresponding page is blank. cpradio provides a CSS solution to remove only the “Uncategorized” link or all category links from the hamburger menu. The solution works for the original poster.
Later, Cozdabuch asks if it’s possible to hide all categories and then display only select ones. P2W asks where to edit the provided code, and jomaxro points to a beginner’s guide to using Discourse themes. However, P2W finds the guide unhelpful and needs further clarification. jomaxro explains that the CSS line needs to be added to the current theme or a theme component.
To remove only the uncategorized category
.hamburger-panel .category-links .category-uncategorized { display: none; }
To remove all
.hamburger-panel .category-links { display: none; }
.hamburger-panel .panel-body-contents > hr { display: none; }
Works like a charm. Thanks! Will the FAQ (New) eventually timeout on its own?
No, it will not timeout. It will disappear only when the FAQ has been read (scroll all the way down).
Is there a way to start with the above solution to hide all, then specifically display only select categories?
where do i edit this code? non-technical discourse user here!
See Beginner's guide to using Discourse Themes for all the details.
that did not help me 
I went into the CSS menu and couldn’t find that line of code to edit. Maybe I need to add it somewhere?
Correct, that line of CSS doesn’t currently exist. You need to add it to your current theme, or a theme component that is included in the active theme.