First, google it, with regard to an issue I read about this morning. (the essense was that a user (who states others have experienced it) did a refresh (essentially clean install) and optd not to keep any files or applications, and ended up with a boot loop issue.
that aside, if you do want to do this, then the best option is to go to settings, update, backup and recovery, and then perform which ever action seems most suited to you