Hi,

Stairdesigner calculates stairs in the European way, dividing the steps and riser heights from start to end to fit within an operational window on riser height, tread width, and the stair rule. The tread width is a calculated value, not a value to enter and calculate from. 

En value can be adjust from menu Tools >Control Values…

But the only way is IF possible..

Reiser height, is to adjust number of Riser
Tread Width , is to adjust length of flight

At the lower end, it would be a dangerous staircase, and at the upper end, it would be difficult for children and the elderly to climb.

If you already deleted this landing for example it stay visible in 3D, and already in use for climb height

But you can disable Riser, and définie an Nil material (100% transparency)

Hope that’s helpful, Alex