Deleting removes a survey for good: its question groups, questions, answer options, conditions and the files uploaded for it, together with its responses and its participant list. There is no undo and no trash. If you only want to stop collecting responses, deactivate the survey or set an expiry date instead. See Stop, pause or deactivate a survey.
Before you delete: export what you want to keep, the survey itself and its responses. See Export a survey and Export your responses.
In the workspace, click the ... on the card of the survey and then Delete.
Check the survey ID in the dialog (1).
Click Delete survey (2).
In the picture: 1 the ID of the survey you are about to delete, 2 Delete survey. Cancel closes the dialog and keeps the survey.
In the workspace, switch to the list view with the list icon at the top right.
Select the surveys with the checkboxes. The survey ID is the first column.
Click Delete in the bar at the bottom of the page.
The dialog asks Are you sure you want to delete all those surveys? Click Delete.
No. Only a file you exported before can bring it back: import the survey structure (.lss) or the survey archive (.lsa). See Import a survey.
Deleting needs the delete permission for that survey. Ask the owner of the survey or an administrator of your site. See Survey permissions.