For touchscreen operation sometimes it is requested that the mouse cursor is not visible.
Therefore there exists the option "Cursor visible" which can be deactivated in Project -> Graphical desing -> Cursor visible

As mentioned in the embedded help:
"ATTENTION: This functionality only works in elements of the control system (pictures, elements, ...) but not with Windows standard elements (title bars, menus, scroll bars, ...). For this the cursor has to be deactivated directly in the operating system."

If you want to complete deactivate the mouse cursor as long as the runtime is running it is possible to do this via the API call ShowCursor().

Private Declare Function ShowCursor Lib "user32" (ByVal bShow As Boolean) As Long

'this event is fired at starting the runtime
Private Sub Project_Active()
    'don't show mouse cursor
    ShowCursor False
End Sub

'this event is fired at closing the runtime
Private Sub Project_Inactive()
    'show mouse cursor
    ShowCursor True
End Sub