You can set RadCalculator's property MemoryButtonsVisibility
in order to hide the Memory buttons. I have tested it with our latest binaries (version 2012.3.1017.1050) and everything works as expected. However, in order to achieve your goal, you can predefine RadCalculator's template and remove the buttons that you do not want to appear. For your convenience I have prepared a sample project showing you the approach. Please find it attached.
All the best,
the Telerik team