In docs/extending_cms/app_integration.rst there is:
If at some point you want to remove this apphook after deleting the cms_app.py there is a cms management command called uninstall apphooks that removes the specified apphook(s) from all pages by name. eg. manage.py cmsmanage uninstall apphooks MyApphook. To find all names for uninstallable apphooks there is a command for this aswell manage.py cmsmanage list apphooks.
But there are no 'cmsmanage' command. There is 'cms' command.