

When it is done, backup the disk image to your online/local backup. Select Save the home folder in a disk image and Click Delete User. Access System Preferences→Users & Groups, and Clock minus button on the bottom in the left panel. First of all, create a new admin account and login with this account. There is an easy way to backup each user account on your Mac. Please also note that this will delete your cookies for any other sites, too. This will stop ie from automatically logging into Gmail.

If you have more than one user on your Mac, and you’re only interested in backing up your own data, just go one level deeper and select your user account from within the Users folder. In the dialouge box that appears, untick everything but 'cookies' and 'passwords'. Each user account contains your Desktop files, documents, downloads, videos, music, and pictures. This will back up your user account, along with any other accounts on the Mac, plus any shared data. When choosing what to backup manually, most importantly look at the Users folder, located by default at Macintosh HD/Users/.

So, If you skip this step, you won’t be able to recover your data if something goes wrong. Note: A clean install of macOS Sierra on the startup drive completely erases all data on that drive including all your files (documents, music, movies, pictures, and even apps).
