With keywords you can arrange your surveys to categories.
You can create a new keyword “folder” just by adding a new keyword to the survey. You can remove a “folder” by removing the keyword from all surveys that have that particular keyword.
There is only one copy of the survey, although it might be displayed in many folders. If you delete a survey from one place, it is removed to the Deleted folder and will be visible only there.
Removing a keyword does not completely delete the survey. If a survey has no keyword, it is still displayed in the My surveys / Shared to me / All surveys folder.