If you see the following warning on your device, it means that you are trying to log out while the currently logged in user has unsent responses. If you proceed, all unsent responses will be deleted permanently.

If you do not want to lose the unsent responses, you will need to ensure you are online, and send the responses, or tap the Delete All Surveys & Unsent Responses on this Device button to delete all of the responses that are currently unsent.

You will then be able to log out.