By Igna Triay, 15 January, 2017 Forum macOS and Mac Apps Hi all, is there a guide in applevis that shows you how to do a clean install of the mac os? thanks Options Log in or register to post comments Comments I'm not sure if there is a I'm not sure if there is a guide or not, but you can follow these steps. 1. Restart your Mac while holding down Command R. 2. Press Command F 5 to turn Voiceover on. 3. Select Disk Utility from the application selection table. 4. In Disk Utility, select your startup disk, usually called Macintosh HD, and click the erase button in the toolbar. 5. When the erase and reformat is finished, quit Disk Utility and select Install macOS from the table. Follow the normal prompts to install macOS on your freshly formatted startup volume. HTH do i Do I have to backup first, or put my files in a usv or somethimg so that they don't get erased? All files will be erased with All files will be erased with a clean install, so backup whatever you want to keep.