If you want to hide the Minimize and Maximize buttons you have two options:
By setting the ResizeMode property to CanMinimize only the Minimize button will be visible. The resize button will get hidden and the resizing will get disabled. By setting the ResizeMode property to NoResize both the Minimize and the Maximize buttons will get hidden, the resizing will also get disabled.
If you want to hide these buttons without affecting the resizing functionality, consider using the approach explained below.
To learn more about resizing the RadWindow read here.
After getting familiar with the template and preparing it for editing, the only thing left is to locate the Button controls that represent the Minimize and the Maximize buttons and to set their Visibility to Collapsed. These buttons have their Name properties set to PART_MinimizeButton and PART_MaximizeButton.