To delete an idea, a moderator needs to change the status of an idea to Removed.
Ideas that have been removed are not visible to users and can be seen moderators if they sort by Removed when viewing ideas in a challenge. From a user perspective, a removed idea has been 'deleted', and removing it allows you to keep a record of what was posted.
To remove an idea:
When you are viewing an idea, in the Moderator toolbar, click Moderation Status.
Select Removed and click save.
If you Remove an idea, the idea and comments are not visible to the idea author (unless they're a moderator!) so they won't be able to see any reason that you add to explain the change in status. It's good practice to contact the user directly to let them know why you've removed their idea.