Some users may see two different RefWorks toolbar options in Microsoft Word. If you see one called "RefWorks - RCM" and then another that just says "RCM", use the one that just says "RCM".
If you only have the 'RefWorks - RCM' one, you should upgrade to the new one (or switch to Zotero now, which the Library recommends).
There are lots of tutorials on how to remove the old 'RefWorks-RCM' plugin. Here is one from another university.