Do not show any Adequate Airports in PPS minimap.

If you just want a blank Adequate Airport list when creating a new flight, then please initially navigate to Data Editor and then ADEQUATE.

In here, just add 1 airport far away from your normal operation area, e.i. ENGM or RJAA and once you create a new flight the system will identify this airport too far away from the route and then nothing will be added and the list is empty.

Note: You might need to restart PPS after you have made the change.