If you open Outlook and click the Tools menu you should see an option from Trust Center and thenAdd-ins, this should let you remove the ESET plugin and anything else that shouldn't be there. There should be a dropdown box labeled Manage and a button that says Go at the bottom of the add-ins screen. You must select Exchange Client Extensions to find the ESET plugin. Click the Go button and look for the ESET plugin. If you see it, remove/disable it and then restart Outlook.
I couldn't find the extension !!!