Hi Mike,

I've discovered a way to do this on a Windows setup, but it's slightly onerous. Be sure to back up your preferences file first if you try this. Steps as below:

1. Ensure Illustrator is closed before starting.
2. Locate Adobe Illustrator Prefs file – in Windows, it's usually in the folder:
   C:\Users\YOUR USER PROFILE NAME HERE\AppData\Roaming\Adobe\Adobe Illustrator 23 Settings\en_GB\x64
   (note that your Illustrator version number may be different).
3. IMPORTANT: Make a backup copy of the preferences file before editing the original.
4. Open the original file in a text editor and search for the /FileList tag.
5. Underneath /FileList are items /file0, /file1, etc. (in my case it went up to /file19 because my recent file preference was set to 20) with various data between the curly braces. Remove all the /file tags except for /file0, and remove all the data from within /file0, being careful to make sure there are opening and closing braces for both /FileList and /file0.
   It should look like this:

	/FileList {
		/file0 {
		}
	}

6. Save the preferences file and restart Illustrator. If an error message comes up, copy the backup file over the original and try again.

If you don't change preferences very often, you could save a copy of the preferences file with the clean file list and just copy it back over whenever you want to clear recent files - it would be easier than doing the above steps every time. At least until Adobe deems it a problem worthy of putting a "Clear Recent File List" button on the Home screen!

Hope this helps you, and others.