Is disowned a legal term?

The term disownment does not refer to a legal process, but to the personal choice to choose not to acknowledge a relationship with a specific individual. However, it's frequently used to refer to the act of renouncing an individual's inheritance rights – in other words, “writing her out” of a will.

When should you disown someone?

When there is no threat of physical or mental abuse and you are living with the person, or persons, you want to disown, you can move into a residence of your own and not let them know your address. You can cease all contact with the family member by refusing to accept any written or electronic communications.