My husband wants to adopt the two kids he raises and supports I get no support from their dad and he has nothing to do with them he sends a text every now and then but other than that no contact I have asked him to sign his rights over and he never answers me can I do it without him

Depending on where in the world you live, no you cannot do this without his consent. Laws vary by location.

How do I go about getting parental rights terminated in Missouri

You contact a family law attorney. He/She will draw up the paperwork for termination of parental rights and adoption. However, if the biological father refuses to give up his rights, and he has the right to do so, adoption will not be possible given the limited information you have posted here.

Your first step is to find an attorney in your area. All adoption cases should use one. The judge is the only one that can terminate his rights and assign them to someone else. While not impossible, it is highly unlikely that this will be done with out any involvement at all of the bio dad.

Depending on where in the world you live, no you cannot do this without his consent. Laws vary by location.

I disagree. Most states allow for step-parent adoptions by involuntary termination of parental rights of the non-custodial natural parent. I have no reason to believe that Missouri is an exception to this.