Joe Miguel, a well-known treasure hunter in Mindanao, executed a Special Power of Attorney (SPA) appointing his nephew, John Paul, as his attorney-infact. John Paul was given the power to deal with treasure-hunting activities on Joe Miguel's land and to file charges against those who may enter it without the latter's authority. Joe Miguel agreed to give John Paul forty percent (40%) of the treasure that may be found on the land. Thereupon, John Paul filed a case for damages and injunction against Lilo for illegally entering Joe Miguel's land. Subsequently, he hired the legal services of Atty. Audrey agreeing to give the latter thirty percent (30%) of Joe Miguel's share in whatever treasure that may be found in the land. Dissatisfied however with the strategies implemented by John Paul, Joe Miguel unilaterally revoked the SPA granted to John Paul. Is the revocation proper? (4%)