Yes you can, it is used to unisnstall all your plugins, enigma2 and openspa. If you want to uninstall an openspa plugin, you can go to SPA Panel - Un/install openspa plugins as well. If a plugin is not right built, it will be impossible to uninstall from these sections. A different way is to uninstall by telnet if you know the name of the package.
To know the name of the package : opkg list-installed |grep name
where name is a word that you think is the name of the plugin
To uninstall package : opkg remove plugin_name
where plugin_name is the name that you got with previous command.