Activity categories are a way of categorizing activities added to DMS.  Activity categories are optional but if they are used each category must be unique;  duplicates are not allowed.  To access the activity categories, select Calendar | Activity Categories as in:

The following screen appears listing all the current activity categories:

From this screen you can delete a category by highlight the category to delete and pressing the delete icon and then verifying the delete.  To add a new category click on the new icon and to edit an existing category click on the edit icon .  The new and edit activity category screen is a simple single prompt screen as in the example below:

After entering a new category or editing an existing category click "Save & Exit" to save the category and exit the screen or click on "Cancel & Exit" to cancel.