Go To: System Settings - Settings - Drop Down List
Use customized drop down lists if you do not want users to add items to auto-generated dropdown lists. Adjust User Permissions to not allow users to add values to the dropdown lists if you are using this function.
Select Category
Select the dropdown category you would like to manage from the dropdown list. Once selected, the dropdown option will appear below.
Click Add More to create new dropdown fields. You may also delete unwanted fields by clicking the trash icon. You may also drag and drop the boxes to re-order.