If you create a will, the will is in effect until it is revoked. In Pennsylvania, a will may be revoked in several ways.
First, creating a new will revokes any prior wills.
Second, you may create a document stating that the will is to be revoked. This document must be executed the same way as a will is to be executed.
Third, you may burn, tear, cancel, obliterate or destroy the will, with the intention of revoking the will. You may also have a third party destroy the will in the same manner, as long as it is in your presence and by your express direction. In this case, two competent witnesses must affirm that this is the case.