It is not advisable to drive with a damaged sidewall. The sidewall is integral to the structure of the tire, providing support and containing the air pressure. If the sidewall is compromised, it can lead to a sudden loss of tire pressure, which can cause the tire to fail while you are driving. This can be extremely dangerous and could lead to an accident. If you have a damaged sidewall, it is best to have your tire repaired or replaced as soon as possible by a qualified mechanic.