One of the previous versions of Ruptela FM-Eco4 light user manual contains information about factory reset:
Factory reset – is a last resort tool and must be used only in critical cases. This function will reset the
devices entire configuration (password included). Factory reset is a process, which requires
contacting the suppliers’ tech support. Without correlating with tech support, you will not be able to
reset your device. This process includes sending your devices IMEI to tech support, after which a
special code will be generated, that must be entered in the factory reset field.
The manual is rather outdated now, but anyway to do factory reset you should contact Ruptela technical support.