Joining (or leaving) the group is done through the User Control Panel. Once there, you click the tab for Usergroups (link here). You should see Show No Support and Show No Tickets in the 'Non-Memberships' list. Select by clicking the radio button on the right, then use the dropdown menu 'Join Selected' (or 'Resign Selected' to leave) and click submit. The pictures below should help illustrate:
Here's the Usergroups tab of the User Control Panel. It shows the two 'Show No' groups in the Non-Membership section.
To join one of the groups (and 'opt out' of or turn off your access to the respective category), select the radio button on the right for the group you'd like and then choose 'Join Selected' from the menu on the bottom right of the page.
Once you've joined the group, it will appear under your group memberships.
To resign from a group (and turn your access back on), select the radio button on the right from the group and then choose 'Resign Selected' from the menu on the bottom right of the page.
[Updated 12/3/15 to include wording for Show No L&F]
