Resources cannot be deleted once they are created. If you have a resource that is no longer with your company and you are no longer in need to view their information, simply make their resource ‘Inactive’.
This can be done by finding the Resource you’d like to make inactive and navigating to the ‘Settings’ information field in the ‘General’ tab. Once here simply click the slide the button next to ‘Active’ and ‘Job Assignee’ to ‘No’. The resource is now fully inactive and will not show up moving forward.