PostgreSQL: Removing nested JSON property

example.sql

-- before:
-- my_json = {some_var: 10, some_nested_ob: {some_var: 10, another_var: 20}}
-- after:
-- my_json = {some_var: 10, some_nested_ob: {another_var: 20}}

WITH subquery AS (
    SELECT my_json #- '{some_nested_ob,some_var}' AS updated_json,
           id
    FROM my_table
    WHERE (my_json -> 'some_nested_ob') -> 'some_var' IS NOT NULL
)
UPDATE my_table
SET my_json=subquery.updated_json
FROM subquery
WHERE my_table.id = subquery.id
RETURNING my_table.id;