Short answer. Yes. Article 920 of the Civil Code lists the loss of parental authority for causes specified in the Code as a sufficient ground for disinheriting a parent or ascendant. If a court terminated your parent's parental authority for a cause recognized by the Civil Code or Family Code, you may disinherit them on that basis.
What the law says
The loss of parental authority for causes specified in this Code
Civil Code, Article 920 — Grounds to Disinherit Parents and Ascendants. Read the full provision →
Loss of parental authority as a disinheritance ground
Article 920(6) provides that the loss of parental authority for causes specified in this Code is a sufficient ground to disinherit a parent or ascendant. This links the disinheritance right to the specific causes for which parental authority can be lost or terminated under the Civil Code and the Family Code — grounds such as subjecting the child to sexual abuse, depravity, criminal conviction, or other serious misconduct. If a court entered an order terminating your parent's parental authority based on one of those causes, Article 920(6) is available to you as a ground for disinheritance.
The causes must be those 'specified in this Code'
The ground is not unlimited. Article 920(6) refers specifically to loss of parental authority for causes specified in this Code — meaning causes recognized in the Civil Code itself (or by extension the Family Code, which governs parental authority today). A court order terminating parental authority on procedural or technical grounds, or for reasons not recognized as Family Code grounds for loss of authority, may not qualify. What matters is that the underlying reason for the termination falls within the recognized causes of loss of parental authority under Philippine family law, not just that a court entered an order.
How to properly execute the disinheritance
Disinheritance must be made in a valid will — it cannot be done informally. The will must expressly name the parent being disinherited and state the cause with clarity. For Article 920(6), the relevant cause is the loss of parental authority and the basis for that loss. Attaching or referencing the court order that terminated parental authority strengthens the disinheritance and makes it less susceptible to challenge. A disinheritance clause that merely says 'I disinherit my parent' without stating a cause is void, meaning the parent would still be entitled to their legitime despite the clause.
What disinheritance does and does not do
A valid disinheritance removes the parent from your list of compulsory heirs — they lose their legitime and any other share of your estate. Their portion does not disappear but passes to others among your heirs according to the law or your will. However, disinheritance does not erase civil obligations between parent and child while both are alive — it affects only inheritance. It also does not automatically bar the parent from inheriting from other members of the family. If you want to ensure your parent does not benefit from your estate, the disinheritance clause must be properly drafted and the will validly executed.