You may favorite any dashboard that you created or is shared with you.
You may not Delete collection you do not own. However, you may simply unfavorite what is shared with you to remove it from your usual lists.
Steps
1. Go to COLLECTIONS > Manage.
2. Click the Favorite icon.
3. To un-favorite, click the Favorite icon.
Example
Go to COLLECTIONS > Manage. Click the Favorite icon next to New Tables. Then go to the Favorites tab.
Un-favorite New Tables by clicking
Favorite again.
Now it is removed from the Favorites tab.