In MongoDB Atlas, deleting regions involves removing data and resources from specific geographic locations where your database is hosted. To delete regions, you typically need to access the Atlas dashboard, select the appropriate cluster, and modify the region settings. Deleting a region can help manage costs and optimize performance by consolidating data to fewer locations. However, ensure that you understand the implications, such as potential data loss and impact on latency, before proceeding with the deletion. Always back up critical data before making such changes.