can't delete unused kext in mojave
System kexts are protected by System Integrity Protection (info)


  Originally introduced with OS X El Capitan, System Integrity Protection, usually referred to as SIP, is a security feature built into the Mac operating system that’s designed to protect most system locations, system processes, and Kernel extensions from being written to, modified, or replaced.


So you won't be able to remove this kext unless you disable SIP which is not recommended.