For Android, MacOS, and iOS, you can easily manage, deactivate, and reactivate private Duck Addresses within the Passwords menu in the DuckDuckGo browser.
If you’re using Windows or the DuckDuckGo browser extension (and alternatively for Android, MacOS, and iOS), you can manage private Duck Addresses individually through your inbox. For example, if you search your inbox for ‘@duck.com’ you should be able to find any emails sent to your inbox via private Duck Addresses. These can be individually deactivated (or reactivated) via the banner at the top of each email.
Prior versions on GitHub.