Man pages matching name pmunloadnamespace in section 3:

pmUnloadNameSpace.3.en	debian 10 / libpcp3-dev
pmunloadnamespace.3.en	debian 10 / libpcp3-dev
pmUnloadNameSpace.3.en	debian 11 / libpcp3-dev
pmUnloadNameSpace.3.en	debian 12 / libpcp3-dev