Did you try doing a search for this in the Reference Guide?
That what's so cool about it....you can find instant answers like this immediately....right from the Help item in the Utility Menu in RMX.
Think of it like Google for RMX questions! :-)
first of all thanks to Ceasefire too for the quick response
i tried with wrong words like 'delete' or 'remove'. for me (italian) it's not always easy to find the right word for a search.
anyway at this point i think a clear part button near groove name could be useful and maybe a 'don't ask again option' on the confirm alert too.