How do I get rid of the legacy system DEVGURU Co, LTD from my computer

FWIW, DEVGURU Co, LTD is the name of a developer, not a legacy extension. There's no need to uninstall legacy extensions until and unless you upgrade to macOS Big Sur once it becomes available.

See: About legacy system extensions - Apple Support

You shouldn't. If you have apps that install them they will break.