1. Open Preferences [CTRL+,]
2. Select "External Editing" tab.
3. Click the drop-down box & Choose the preset you want to delete in the "Additional External Editor" : "Preset" box.
4. Click the drop-down box a second time for the menu and click on "Delete Preset....your selection in 3."
It defies logic, but to delete a preset you first have to choose it in the "Preset" selection box.!
Thank you, got it!!