I had a look at gpedit.msc and there seems to be no restrictions that you
can apply that disable the Print menu and toolbar button. Policy
restrictions would be the normal way of reducing IE's functionality.
The webbrowser activeX control has not properties or methods to disable this
feature, but if you host the control in your own application then you can
choose not to give your users print functionality. I think this is the only
viable solution.
Alternatively, create your own BHO and obtain the hwnd to IE's menus and
change the state of the Print menu to disabled. Quite a complicated and
advanced method. But achievable. You will still be left with the Print
button on the Buttons toolbar though!