Most of the default questions of the survey can be deactivated (not deleted), if you don't feel that they serve a purpose in the online survey on your website. Simply uncheck the box by the question to instantly remove the question from your survey. The question will be moved down the page to "inactive question" from where you may activate it again whenever you feel like it.
Questions that you have added to the survey yourself, you can either deactivate or delete. But as a general rule you should always just deactivate a question and not delete it - unless you have never collected any answer to this question and are 100% sure that you will never use the question again. Once you delete a question the answers collected to it will no longer appear in your reports.
Please note that some questions like "overall website satisfaction", "Gender" and "Age" cannot be deactivated. These questions are used in most standard reports, click tracking and Google Analytics integration. So it's important that these questions are asked in the online survey to make sure that you are able to benefit from all the features of UserReport.