How do I clean install Catalina?
How do I carry out a fresh/clean install of Catalina?
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Backup any files you want to preserve (or clone the whole drive as a backup to an external drive). Create a bootable flash drive, boot from it (with a new Mac you may have to enable external booting via the Recovery boot first), launch Disk Utility, make the internal SSD _device_ (not just the volume) visible and erase it as APFS (with GUID partition map), then install Catalina.
https://support.apple.com/en-us/HT201372
