What is the cost to reverse an adoption when a child is now an adult and wishes it to be done?

I grew up adopted as a child and now that I am an adult I would no longer like to be adopted. My adoptive mother is creating problems with my children and even attempts to manipulate me as an adult. I am a 24 year old, married lady with 3 children. I would like to eliminate her out of my life but I would like to know the amount this would cost me.