Singh was given a ceremonial send-off on Friday morning, but sources said that the possibility of his getting a three-month extension could not be completely ruled out.
In April 2015, the then DGP Arvind Jain was given a ceremonial send off in the morning and the same evening, just before the traditional high tea, he was given a three-month extension.
Interestingly, Singh has scotched rumours about his extension, and said that he would retire on January 31.
O. P. Singh has had an eventful tenure and will be remembered for introducing the police commissionerate system in two districts of the state.
He also has the credit of ensuring peace in the state after the Supreme Court verdict on Ayodhya temple, and the incident-free Kumbh Mela.
Sources also said that Chief Minister Yogi Adityanath may also accept Singh's proposal of posting a senior IPS officer as the principal secretary (home).
An IPS officer is already serving as a secretary (home), but after the introduction of police commissionerate system, Yogi is likely to post an IPS officer as principal secretary (home).
This has been a long pending demand of the IPS cadre in the state.
Meanwhile, the Uttar Pradesh government, which earlier sent a panel of five IPS officers to the UPSC for selecting Singh's successor, has now sent the names of all DG-rank officers posted in the state or on Central deputation.
The names of three officers, who will be promoted to the DG rank after retirement of O. P. Singh and DG (Intelligence) Bhavesh Kumar Singh, DG (Special Enquiry) Mahendra Modi, were also sent to the UPSC. All three are retiring together on Friday.
The move to send all the names was taken by the government after DG Jawaharlal Tripathi filed a writ challenging non-inclusion of his name in the list despite him being one of the top three senior-most IPS officers posted in the state.
Meanwhile, speculations are rife that O. P. Singh is likely to be appointed as the new chief information commissioner of the state after retirement.
( With inputs from IANS )