According to Saint Alphonso Maria de Ligouri (1696-1787), it is possible to break a pact with Satan, even if it has been signed in blood.

The following steps must be followed:

•  Renounce and abjure any contract with Satan.
• Destroy all writings, talismans, charms, etc., connected with the black art.
• Burn the written contract, or declare you regret and reject it.
• Make restitution for any harm done, insofar as is possible.