A Will can be revoked by the following acts/cirsumstances:

a) Marriage
A Will is revoked by a marriage or re-marriage (unless the Will is made in contemplation of a particular marriage). Divorce or separation does not revoke a Will.

b) Destruction
A Will is revoked when the Testator destroys the Will physically with the intention of revoking it. Accidental or malicious destruction by a third party does not constitute revocation.

c) A later Will
A subsequent Will would automatically revoke an earlier Will, whether or not a revocation clause is included in the later Will. The Testator can also revoke a Will by making a written statement of his intention, signed in the presence of 2 witnesses.

d) Conversion to Islam
A Will is revoked when a Non-Muslim person converts to Islam because the distribution of his/her estate will automatically follow the Faraid distribution.