Thank you for writing.
In order to change the default dock state of a window, you should set its DockState property:
toolWindow1.DockState = Telerik.WinControls.UI.Docking.DockState.AutoHide;
More information about how to create a RadDock at Runtime and which are the allowed dock states can be found here: Creating a RadDock at Runtime
I hope this helps.
the Telerik team