To upgrade the program to a later version, it is necessary to uninstall the previous one with the following instructions.
To uninstall the NextFEM tab from the Excel Ribbon, remove NeXel from Control Panel/Programs and Features.
To remove feature loading, from Excel's File Menu select Options, then Add-ons. At the bottom, from the Manage menu, select Excel Add-ons and click Go. From the mask that appears, uncheck "neXel."