How do I delete a function in namespace .z?

The usual way to delete a function – any entity, for that matter, is

    delete entity from namespace


    delete foo from `.

However, .z is a special namespace, so delete doesn’t work:

q).z.ts: {47}
q)delete ts from `.z

There is a special command just for removing elements from .z:

q)\x .z.pi

See \x (expunge).