Can someone please let me know how I can change the field names (not the alias) in ArcGIS 10.2. I already found this page on ArcGIS support: "Renaming shapefile fields (Defense Mapping)" but there is is not "Defense Mapping" on Customized Mode Categories In my ArcCatalog!

Can you please let me know how I can have access to Defense Mapping or how I can change the field names? Thanks