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.