re: #84 KGxvi

Technically the War Department and the Post Office Department were disbanded. The War Department was superceded by the Army and Air Force Departments, which later along with the Navy Department were combined into the Defense Department. The Post Office Department became the Postal Service.

While not quite a cabinet-level department, the Board of Tea Examiners was eliminated in 1996, after a 99-year run.
nytimes.com