DO
BEGIN
FOR i IN SELECT table_name FROM information_schema.tables
LOOP
   IF SELECT column_name FROM information_schema.columns WHERE table_name = 'i.table_name'
 THEN
   ALTER TABLE i.table_name RENAME COLUMN old_column_name TO new_column_name
END IF;
END LOOP;

DO
$$
DECLARE
    rec record;
BEGIN
    FOR rec IN
        SELECT table_schema, table_name, column_name
        FROM information_schema.columns
        WHERE column_name = 'x'
    LOOP
        EXECUTE format('ALTER TABLE %I.%I RENAME COLUMN %I TO newname;',
            rec.table_schema, rec.table_name, rec.column_name);
    END LOOP;
END;
$$
LANGUAGE plpgsql;

DO
$$
DECLARE
  rec record;
BEGIN
  FOR rec IN
  SELECT table_schema, table_name, column_name
  FROM information_schema.columns
  WHERE column_name = 'my_column_name_to_drop'
  LOOP
    EXECUTE format('ALTER TABLE %I.%I DROP %I;',
                   rec.table_schema, rec.table_name, rec.column_name);
  END LOOP;
END;
$$
LANGUAGE plpgsql;