Note.
Reading DesktopFile.Actions returns an array of the Keys from the Actions filed so you cannot modify it directly. To modify you must write the DesktopFile.Actions

For example to remove the second item..

This will not work..

MyDesktopFile.Actions.Remove(1)

But this will...

Dim sKeys as String[] = MyDesktopFile.Actions
sKeys.Remove(1)
MyDesktopFile.Actions = sKeys

For a clearer example take a look at the gambas.desktop file that installs when you install Gambas...

Reading the DesktopFile.Actions of the gambas.desktop file would return ["QT4", "QT5", "GTK3"]

[Desktop Entry]
Name=Gambas 3
Exec=gambas3
GenericName=Gambas 3 IDE
GenericName[fr]=EDI Gambas 3
GenericName[ru]=Gambas 3 IDE(ИСР)
Comment=Gambas3 Integrated Development Environment
Comment[fr]=Environnement de développement intégré Gambas 3
Comment[ru]=Gambas 3 IDE(ИСР) - альтернатива для Visual Basic
Icon=gambas3
Terminal=false
Type=Application
Categories=Development;IDE;
StartupNotify=true
Actions=QT4;QT5;GTK3

[Desktop Action QT4]
Name=Run with QT 4
Name[fr]=Exécuter avec QT 4
Exec=env GB_GUI=gb.qt4 gambas3

[Desktop Action QT5]
Name=Run with QT 5
Name[fr]=Exécuter avec QT 5
Exec=env GB_GUI=gb.qt5 gambas3

[Desktop Action GTK3]
Name=Run with GTK+ 3
Name[fr]=Exécuter avec GTK+ 3
Exec=env GB_GUI=gb.gtk3 gambas3