A big-bike riding riot policeman facing multiple charges after killing a doctor on a zebra crossing left the monkhood with his father after attending the victim's cremation on Wednesday.

Pol L/Cpl Norawich Buadok and his father, Pol Sub Lt Nikom, returned to being laymen at a ceremony at a temple in Bangkok.

The pair disrobed on their return to the temple after attending the cremation of Waraluck Supawatjariyakul, an ophthalmologist at Chulalongkorn University.

Dr Waraluck was killed when Pol L/Cpl Norawich, riding a Ducati motorcycle, struck her while she was on a zebra crossing on Phaya Thai Road in Ratchathewi district on Friday.

The incident angered the public as video footage showed the biker made no attempt to stop at the crossing.

The doctor was killed three days before her 34th birthday, and family members, friends and well-wishers sang 'Happy Birthday' in front of her coffin at the temple on Monday.

"This is the last time for the family to send her to heaven," her father, Dr Anirut, said. "It will take some time for all the family members to recover (from the loss) and adjust to life without her."

Pol L/Cpl Norawich was under pressure to leave the monkhood after the National Office of Buddhism opposed his ordination due to the charges against him.

His father said after disrobing that they would to continue to wear all-white outfits and observe the precepts at home for another three days to honour the late doctor.

Police have pressed seven charges against the killer cop.