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. To see any that are currently disabled you can check the Show disabled box.
To disable an active achievement, you will click on the ellipsis to the far right of the achievement and select Disable.
Active Achievement
Disabled Achievement