This receptacle on a lamppost was 47 years old at this point and "hadn't worked in about 5 years."
Attempting to remove the trim cover revealed a badly disintegrated receptacle...
...still having...
...live terminals. Finding an exterior receptacle/trim combination matching the radius of the existing post would have added a significant amount of time to the job, and the homeowner was not interested in a whole new lamppost...
...so the option chosen was to remove what remained of the receptacle, cap the electrical, and abandon it behind a modified blank exterior trim cover.