To enable or disable the forum sidebar please follow these instructions
Select User Control Panel
Login to your retrobike account (if you don't have one you'll need to register) and click 'User Control Panel' which can be seen top right below the main navigation.
Select Board Preferences
From the right hand options menu select Board Preferences.
Change My board style
Update 'My board style' (dropdown circled in red) to your desired template.
subsilver2 sidebar will show the right hand sidebar.
subsilver2 does not have a sidebar.
Click submit. Refresh your browser. Job done.