How to center your cursor?

What is the easiest way to center your cursor whilst in-game?

You will need to get the size of your screen somehow and then use that to find the mid point of both axis. Then use the central values to set your cursor position:

FVector2D screenSize;
GEngine->GameViewport->GetViewportSize(screenSize);
int centreX = screenSize.X / 2;
int centreY = screenSize.Y / 2;