Making sets private
Sets are public by default, but you can make your sets private at any time. Private sets will not appear in search results and can only be viewed by the set creator.
How to make a set private
Go to the main set page and click "Edit" on the upper right.
On the next page, click the "Visible to everyone" button to the right of the set title.
Choose "Just me" from the "Who can view?" options. Then click "Save."