Paid authors may delete their existing shares individually. From the command center, authors can swipe to delete any created share. From that point all, the share is deleted from the cloud and no one (concluding the author) can access it or edit it ever again. You have more options to delete existing shares from the edit page, command center or when accessing share links in the wild.
Authors can also use the “nuclear option“ of deleting all of their shares, like a panic button, in the account tab. This clears all previous shares and access, access rules, controls and content. The subscribing author must respond to an out-of-band token to confirm and consummate this mass deletion.