1.Uninstall all PMDG airplanes if you more than one
2. Go to sim folder and delete PMDG Folder
3. Go to P3D\SIMOBJECT\AIRPLANES folder and delete all PMDG folders
4.go to \appdata\roaming and delete PMDG
5. Go to \APPDATA\ LOCKHEED MARTIN delete all PMDG FOLDERS (to access appdata type %appdata%)