Removal of residual com.sophos.nke.swi and com.sophos.kext.oas from Mac OS Sierra

I am having problems with populating web images running Mac OS 10.12.6.

Apple tells me that this is due to residual files from a prior Sophos Home Edition installation - even after the produce has been uninstalled.

The files are:

com.sophos.nke.swi and com.sophos.kext.oas

I cannot find these on the machine however they show up on tracers that Apple uses to diagnose the problem. 

They are unable to tell me where to find them or how to remove them.

Thanks very much.