You are going to have to unfollow a creative if you want to remove them from your Dashboard.
From your Dashboard, hover over their key image. Click the three dots, select "Manage", and click "Unfollow" within the Manage modal. If you're on the creative's profile, you can pull up the Manage modal by clicking the "person" icon underneath their status.
The creative will no longer show up on your Dashboard, unless they're part of a Team list or Curated Playlist.