The first step is to click on Manage at the bottom left corner of SalesScreen.

A menu will pop up, where you can proceed to click on Achievements under the Gamification headline:

Once on the Achievements management page, you will get an overview of all the Achievements which have been created and are either active or inactive. To set an Achievement as inactive/active, click on the corresponding On/Off (green/red) switch:

Active Achievement

Inactive Achievement