Call Function C++ Class ( No Blueprint )

From HUD?

APawn* Pawn = GetOwningPawn();

if(Pawn && Pawn->Controller && Pawn->Controller->IsA(AtdaController::StaticClass())) {
          ((AtdaController*)Pawn->Controller)->showMouseCursor();
}

All classes related to eachother in anyway usally keep refrences to eachother, so use API refrence to check how to get specific object of a class.