Postgres jsonb: remove key from all entries

gistfile1.txt

# Function
CREATE FUNCTION jsonb_merge(JSONB, JSONB) 
RETURNS JSONB AS $$
WITH json_union AS (
    SELECT * FROM JSONB_EACH($1)
    UNION ALL
    SELECT * FROM JSONB_EACH($2)
) SELECT JSON_OBJECT_AGG(key, value)::JSONB FROM json_union;
$$ LANGUAGE SQL;

# Command
Update he_user_meta set value = jsonb_merge(value, '{"game_state_version":null}');