How best to do a a clean install of Mac OSX Catalina

Your Disk Utility image shows on the Volumes in the left hand panel.

Click on the View button under the red traffic light top left and select Show All Devices.

Now you will see the Disk and the volumes are indented.

Highlight the Disk and then click Erase.

Give the Disk a name

Format: APFS.

Scheme: GUID Partition Map.

Click Erase.

When done your macs hard drive is now ready to do the installation.

Quit Disk Utility.

You should always have frequent and regular backups. It is impossible to recover accidentally deleted data from an SSD. Plus an SSD can fail at any time without any warning signs. The easiest way would be to use the built-in Time Machine backup feature provided by macOS.

Once you have a backup, then you can perform a clean install of macOS by using these instructions:

https://support.apple.com/en-us/HT208496

Another option would be to clone the drive using Carbon Copy Cloner.

On first boot Setup Assistant will prompt you whether to migrate any data. Since you want to do a clean install I would only migrate the user folder(s). Or you could create a new user account and manually migrate your data back from the TM backup or clone.

I don't use Time Machine, but I believe this should work. May be another more knowledgeable contributor could chime in regarding Time Machine.

You can boot the Mac using Recovery Mode, Internet Recovery Mode, or from a bootable macOS USB installer.

On first boot Setup Assistant will prompt you whether to migrate any data. Since you want to do a clean install I would only migrate the user folder(s). Or you could create a new user account and manually migrate your data back from the TM backup or clone.

I don't use Time Machine, but I believe this should work. May be another more knowledgeable contributor could chime in regarding Time Machine.

For a clean install, I would manually move files rather than using Migration Assistant. Personally, that’s how I set up new Macs.

Files can be copied from a clone or a Time Machine backup. Personally, I use SuperDuper! for cloning (same functionality as CCC). The free version makes a fully functional clone, which will work for this purpose.

To manually copy from a TM backup, connect the drive and navigate through the Backups.backupdb file (or you can set System Preferences > Time Machine to show TM in the menu bar, then option-click it and you can browse the backup in the TM interface).

neuroanatomist wrote:

For a clean install, I would manually move files rather than using Migration Assistant. Personally, that’s how I set up new Macs.

That is definitely the safest option since users don't have any granular control over Migration Assistant, but for some users migrating the user account(s) may be an acceptable option if the issues the OP is trying to over come are caused by the apps or their system extensions/Launch Agents.

HWTech wrote:

That is definitely the safest option since users don't have any granular control over Migration Assistant, but for some users migrating the user account(s) may be an acceptable option if the issues the OP is trying to over come are caused by the apps or their system extensions/Launch Agents.

Agreed. I am, admittedly, a bit conservative in that regard. In regard to backups, too...I have four TM backups of all the Macs in my house (not as bad as it sounds, two are just a RAID1 NAS, and I keep another pair of backups to rotate one offsite, in my desk at work; used to just keep one offsite and bring it home overnight to update it, but with COVID-19 I only go into the office once a week at most).