Can they revoke Peace Prizes?
No.
"The Nobel Committee, all Norwegian citizens appointed by the country’s Parliament, has never rescinded a prize and will not in Ms. Aung San Suu Kyi’s case either, said Gunnar Stalsett, a former committee member.
“A peace prize has never been revoked and the committee does not issue condemnations or censure laureates,” said Mr. Stalsett, a former politician and bishop who was a deputy member of the committee in 1991, when Ms. Aung San Suu Kyi received her award.
“The principle we follow is the decision is not a declaration of a saint,” Mr. Stalsett said. “When the decision has been made and the award has been given, that ends the responsibility of the committee."
https://www.nytimes.com/2017/09/04/world/asia/myanmar-rohingya-suu-kyi-.html