First, under the law and by extension of his fundamental human right, Oyetola does not have to vacate office IMMEDIATELY.
Subsection 5 of Section 285 of the 1999 Constitution and through its First Alteration via the Electoral Act 2010 says:
“An election petition shall be filed within 21 days after the date of declaration of results of the election.”
Adeleke satisfied this by filing his petition before the expiration of the TWENTY-ONE days after Oyetola was declared.
Now, Subsection 6 of the Act says: “An election tribunal shall deliver its judgment in writing within 180 days from the date of the filing of the petition (six months).”
The Tribunal had met this because it would have been SIX months tomorrow that Oyetola was declared winner. (September 27, 2018).
And Subsection 7 says: “An appeal from decision of an election tribunal or Court shall be heard and disposed of within 60 days from the date of the delivery of judgment of tribunal.”
Implication: Oyetola has SIXTY days (counting from the day the Tribunal declared him a usurper, TWENTY-ONE of which he must file his appeal) and those 21 days must be within the original 60 days for the appellate court to determine the merit or otherwise of his appeal.
If after those 60 days, Oyetola failed to file his appeal and the appeal has not also heard it, he will be REQUIRED by law and COMPELLED by extant injunctions to vacate office!
He still has the right to go to the Supreme Court if the appellate court dismisses his appeal. But again, WITHIN A STIPULATED TIME which is also SIXTY DAYS including filing of notice.
Therefore, technically and since the mandatory 60 days have not lapsed, Oyetola remains governor of Osun State.