I have been wanting to get my ex husbands rights taken away from him. See he is incarcerated in the state of Texas for sexual assault to a minor child. How would I go about getting his rights terminated from him?

Please check the following website for additional information for your state:

State Statutes

Choose under the category Child Welfare: Grounds for Involuntary Termination of Parental Rights.

According to the Texas state statute there:

The court may order termination parental rights if the court finds by clear and convincing evidence that the parent has:

Been convicted of any of the following crimes that caused the death or serious injury of a child:
Murder or manslaughter
Assault, sexual assault, aggravated assault, or aggravated sexual assault
Injury to a child or abandoning or endangering a child
Indecency with a child or prohibited sexual conduct
Sexual performance by a child or possession or promotion of child pornography
Continuous sexual abuse of a young child

Again, please review the website in detail for more information regarding your situation and the state statutes for your location.