I had the problem of kexts still loading after I deleted a 3rd party software that had no uninstaller. A good advice in the first place is to use ForkLift2 to remove such software. (When you try to delete something from the Applications folder from ForkLift2, it will search for kexts it uses and offer to remove those too along with some other things like libs.) If you are past this point and the kexts are still loading for the removed software and they are loaded from StagedExtensions, then disable SIP in recovery mode, reboot, and 'sudo kextunload' then 'sudo rm -rf' the extensions in question. Then do 'sudo kmutil clear-staging' and reboot. I also recommend Objective-See KextViewer to ease finding and getting details about loaded kexts. It is a free, open-source software. Once rebooted the extensions likely will still load, but this time not from StagedExtensions, but from their normal location, e.g. '/Library/Application Support/...' or somewhere else. Repeat the kextunload and rm -rf for them and reboot. This procedure helped me get rid of them for good. Don't forget to enable SIP once you finished!