Since its a company phone (they own it I assume) then I would just send it back to your company IT and say they need to clear and reset it for you. If they are issuing company iPhones, they must have some mechanism for dealing with this, as every iPhone they issue will likely be activation locked to the current employee. If they are not using a managed deployment, then they need to start using one.
Either way, you cannot do anything yourself about disabling activation lock. Apple will not help you with that as you are not the original purchaser or legal owner of the device. Someone at your employer may be able to get Apple to help, if they have documented proof of original retail purchase of the device. Or they can contact the previous employee.