In this article, we’re going to show you how to perform a clean install of macOS. There are a number of reasons why you might want to do a clean install:
• You might want to reinstall the operating system in order to correct problems with your Mac – doing a clean install may be a good option if your Mac is running slow or otherwise misbehaving.
• Doing a clean install allows you to clear away old files that you might have been accumulating for years before installing the operating system onto a freshly formatted disk.
• A clean install is also something you should do before selling your Mac or passing it on. It allows you to remove all your data from your Mac and return it to factory settings for the next person.
• A clean install is also something many computer users resort to when they are trying to get rid of a virus (although there is a lot of debate about whether there are viruses on the Mac).Whatever your reason, a clean install of macOS might solve a lot of problems.
Read more at Macworld.com