To Hide a Category

Hide where?
If you mean hiding it form being displayed in the menu on the sidebar – read about the template tags and their parameters:
https://codex.www.ads-software.com/Template_Tags#Category_tags
If you meant hiding posts in a certain category from the main page (and being displayed only when clicking on the category name) – yes, there are several plugins.
Like this one: https://ryowebsite.com/?p=46

Heres the updated URL for the last plugin that moshu posted:
https://ryowebsite.com/wp-plugins/category-visibility/