Can't delete without CASCADE

Hi, simple problem but can't figure it out - I have two tables connected via foreign keys. Deleting a person causes this error:
message: 'update or delete on table "persons" violates foreign key constraint "training_jobs_person_pk_fkey" on table "training_jobs"'
}


I tried running this to fix:
ALTER TABLE public.training_jobs
DROP CONSTRAINT training_jobs_person_pk_fke,
ADD CONSTRAINT training_jobs_person_pk_fke
    FOREIGN KEY (person_pk)
    REFERENCES persons(person_pk)
    ON DELETE CASCADE;


but it errors out.
Failed to run sql query: constraint "training_jobs_person_pk_fke" of relation "training_jobs" does not exist


Help?
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