If you go to the page you just mentioned, you see a list of Categories you have created. Behind each category, you have a checkmark, or across, you can click on that icon to enable or disable the category. If it's a subcategory, then you need to click on the magnifying glass under actions to expand the list.
Edit History
If you go to the page you just mentioned, you see a list of Categories you have created. Behind each category, you have a checkmark, or across, you can click on that icon to enable or disable the category.