Managing a category very straightforward, you have two options which are edit and archive.
Path: Space > Ellipse Icon > Settings > Categories
Select your desired space to see the Ellipse Icon.
To manage the category click the Ellipse Icon on the right of the category box and click on the Edit option to do the editing.
Now you can edit the category details then click the Submit button.
Next to archive the category click the archive option.
You can view the archive category by clicking the Filter button.
Path: Filter > Archive
For the archive category you can either restore or delete. To restore, click the restore option.
Next to delete, click on the delete option.