How to disable Win key shortcut?

I want to assign Win + U to a macro, but the Windows Utility
Manager keeps overriding it. In other words, even though I
assign that key combination to what I want through a macro
program, using the combo still launches the Utility Manager,
and not the program that I want.

Is there a way to disable this, which appears to be a system
default?

In fact, I'd like to be able to disable any default Win key
combination. Is there a way to do this, and if so how?

Thanks.
--

Bob S.