You can remove the unwanted fillings using the option available in the
Results -> Results tab. Select the three dots button,

and then a button for removing all the responses will appear.

If you want to delete an individual responses, the Delete sheet option is available in the Results -> Responses tab.

Removing results is also available in the Results --> Responses tab. Select the three dots and then Delete the responses.

A message will appear asking you to confirm the deletion of the fills. You can decide whether you want to remove only completed or all responses.