The name on your airline ticket must match the name on your passport or other documents that have been authorized by the government. Moreover, you might not be allowed to board your aircraft if it doesn't match. Therefore, in accordance with Allegiant name change policy, you must start the name correction or alteration process on your ticket. You can utilize the customer service phone number or visit the official airline website for additional updates. If they are unavailable, you can contact the consolidation desk at +1-800-865-1848 for assistance.
Visit at: https://www.flyingrules.com/name-change/allegiant-air-name-change-policy