There’s no limit to how many categories you can create, so go wild - add as many as you want! Head to Settings > Categories to get started.

Whether your forum discusses sports, business, products, services, or anything else, adding categories helps you organize discussions.
Create a list of category discussions that are logical, relevant and easy for your forum members to follow.
What do you mean by adding more categories like you are giving access to every new user that he can add anything. But if you want some help you can https://prowritingpartner.com/papersowl-com-review/ from here they can help you with this at good rates.