Microsoft account help

Reset a Windows 10 deviceBack up any info that you want to save. Select Start​ > Settings  > Update & Security  > Backup  > Add a drive, and then choose an external drive.After you’ve backed up the info you need, select Start​  > Settings  > Update and security  > Recovery.Under Reset this PC, select Get started, and then follow the instructions on the screen. Resetting your device removes your files, settings, and apps, then reinstalls Windows.

Source: Microsoft account help