What should someone suffering from obsessive-compulsive disorder do if they are certain that wind was emitted from them during ablution after washing the face, which forces them to repeat ablution multiple times?

The cure for obsessive whispers (waswas) is to disregard them and pay them no attention. If what you mention about passing wind is an obsessive whisper, then completely disregard it. If you are unable to control the emission and find time for Wudu (ablution) and prayer, then perform Wudu for each prayer after its time has begun, and pray the obligatory prayer and whatever supererogatory prayers you wish, and what is emitted from you will not harm you. Know that the religion of Allah is ease, and that Allah is gentle with His servants, merciful to them, and does not burden them with what they cannot bear. It is obligatory upon you to repent to Allah Almighty and to make up for the prayers you missed, and to adopt means of treatment by disregarding obsessive whispers and paying them no attention. There is no harm in consulting trustworthy doctors.