Severing ties with child

I have 2 children born out of wedlock in the Philippines. Since then, I do not had custody of them and their surnames follow the father. The children don't want me either. Now, the children want to study overseas and still, under the law, need my consent to undertake responsibility. I have been working overseas for many years now and I do not want to take responsibility anymore for them, as this situation is unfair to me. Hence I would like to sever ties with the family lawfully