ALTER TABLE -- how to add ON DELETE CASCADE?

I have table A with a column AA which references table B's primary
key BB, and I want to alter column AA to delete on cascade.

    ALTER TABLE A COLUMN AA ADD CONSTRAINT DELETE ON CASCADE

is what I tried with a zillion variations, all reporting syntax
errors.

\h alter table seems to be missing any way to add a constraint to a
column.

Or maybe this isn't a constraint ... does seem like maybe the wrong
name, but I can't think what else it would be called, and the other
choices shown with \h seem even less likely.

Your assiatnce is much appreciated.  I would gladly send you some
Oreos or Ginger Nuts :-)

--
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     Felix Finch: scarecrow repairman & rocket surgeon / felix@crowfix.com
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