You can delete your respondents’ answers. To do so, go to the “Results” module of your questionnaire, and click on the “Results per respondent” tab:
In order to delete your respondents’ responses, tick the resports you wish to delete and click on “Delete Respondents”. If you wish to delete all the respondents located on one page, tick the box located on the left of “Start date” and click on “Delete Respondents”.