Do this at your own risk. It works for me and I hope it works for you too.

using kextstat|grep sophos you will find 3 sophos kexts. using kextfind you could find these kexts are located at:

/Library/Extensions/SophosFileProtection.kext
/Library/Extensions/SophosPortInterceptor.kext
/Library/Extensions/SophosWebProtection.kext

now mount the file system as read-write

$ sudo mount -uw /

remove them all

$ sudo rm -rf /Library/Extensions/SophosFileProtection.kext
$ sudo rm -rf /Library/Extensions/SophosPortInterceptor.kext
$ sudo rm -rf /Library/Extensions/SophosWebProtection.kext

reboot your macOS, during the shutdown I met a kernel panic.

now remove the application files (maybe this step could be performed before the first reboot)

$ sudo mount -uw /
$ sudo rm -rf /Library/Sophos\ Anti-Virus

reboot again, during the restart, I got a panic once again, reboot again, everything’s fine.

bye sophos.