As an added layer of security, only Workspace Admins can delete Circles that contain content or members. Empty Circles (ones where you haven't yet uploaded content or invited anyone) can still be deleted by the Circle creator.
If you simply want to remove a Circle from your home page view, inactivate your membership instead. This removes the Circle from your list while retaining all uploaded media (including content you've added) and other members. You can rejoin at any time by selecting the Join Group Circle option.
f a Circle truly does need to be deleted (for example, if a duplicate was created), please reach out to a Workspace Admin for assistance.