Most ingrown hairs and hair bumps will usually go away on their own within a few weeks to a few months.
When you have an ingrown hair or ingrown hair bump it's best to apply a warm compress daily and just give it time to allow it to go away.
You can also use some skin creams to help soothe the area and prevent infection of the area and just wait it out.
Sometimes I've had the ingrown hair bump go away within a few weeks while another one lasted a couple months but they do eventually go away on their own.