Revocation must be effected only in the manner prescribed by statute; there can't be an oral revocation.
Statute Part 1
20 Pa. C. S. A? 2505 provides that no will or codicil can be revoked or altered other than: 1 By some other will or codicil in writing;
Statute Part 2
2,. By some other writing, declaring the same, executed and proven in the same manner required of wills; or
Statute Part 3
3. By being burnt, torn, canceled, obliterated or destroyed, with the intent and for the purpose of revocation, by the testator himself or another at his direction.
Statute Part 4
4. If the act of revocation is by some other person, it must be proven by the oaths or affirmation of two competent witnesses.