How to correct slight facial asymmetry caused by extraction of a molar tooth?

Asymmetry. If you have a soft tissue contour problem because of missing teeth, the teeth should be replaced by your Dentist or a Prosthodontist. If the asymmetry is because of a major malocclusion, see an Orthodotic Specialist. If asymmetry caused by skeletal imbalance the services of an Oral Surgeon will be required. Correction may be best provided by all three working as a team.
Tooth replacement. In the 1920s actresses were encouraged to have their molars removed to create a sunken face affect. Thankfully it no longer happens. Missing back teeth can be replaced with implants and a crown in many cases. Bridges may not work as they need at least two teeth to support them. Partial dentures that are removable may also restore symmetry, but are the poorer choice. It may also be muscle size.
Replace the tooth. You have different options to replace the tooth. The options are a partial denture, bridge or a dental implant. Consult with your dentist to determine the best option for yourself.