How do I remove duplicate copies from a cloud account?

Select the account under Cloud & remote, then choose how much to clear:

• Remove just this copy — the button on a single copy.
• Keep best, remove … — keeps the suggested copy in that set and removes the others.
• Clean all … sets — does every set in the account in one step.

Each asks for confirmation, naming the copy that stays and roughly how much space is freed in the account. Just before removing anything, the copy you're keeping is re-checked in the account itself, and files are removed one at a time — never a whole folder.