I'd like to factory reset my mac (which is running El Capitan 10.11.6), while also updating the operating system. Here's what I've done (i.e. steps from this website) in order to create a bootable installer:
Downloaded the Mojave installer from app store
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
When I do this, I get the error message "To use this tool, you must download the macOS installer application on a Mac with 10.12.5 or later, or El Capitan 10.11.6. For more information, please see the following: https://support.apple.com/kb/HT201372"
How can I update the operating system while also doing a factory reset? Thanks in advance.