IdeaScale offers a way to mark certain posts as "Off Topic". When ideas are marked as Off Topic, the idea is placed into a special category in a different part of your community. This category is not included in the "Top Ideas" or "Recent Ideas" view. This is a great technique for moving controversial ideas off to a separate part of your community, without completely deleting the idea (and thus running into free speech issues).
Community administrator has ability to show or hide Off-Topic link along side campaigns in right navigation of community home page from given path:
Customization>> Customize Site Behavior>> General>> Show "Off Topic" Link Alongside Campaigns
How do I mark an idea as off topic?
Marking an idea as off topic is the same process as changing idea stage. Once logged in as a moderator, click the "Moderate Idea" link next to the idea, and then choose "Off Topic" from the dropdown menu.
Idea submitter maybe notified by idea status change email notification when Idea Status change to Off-topic stage