My daughter's father wants to voluntarily terminate his rights all of a sudden. Before he has always said "I want to be a part of my daughter's life." That he will always want to be involved with her and her well being and such and such.. Everything that a good father would say... Well he got married and now has another baby (4th one) on the way and out of no where want to give up all rights to our little girl... I'm not a hundred percent sure what this is all about but I have a really good feeling that it is all about him wanting to get out of paying child support for her cause he has to pay over 8 hundred a month... Is it possible for him to just voluntarily have his rights terminated and get out of paying support? Can he voluntarily terminate his rights without any consent from me? I need any info on laws on this for the state of Missouri... Please!

Before posting on a site like this it is usually a good idea to browse around first and see if there are similar questions that have already been answered. Had you done so, you might have found this sticky:
https://www.askmehelpdesk.com/family-law/signing-over-rights-read-first-116098.html

Among thousands of threads asking the same question.

There is this myth that a parent can just sign away their rights to a child, but its nothing more than a myth. Rest assured that he will not be able to stop support

No he can not just sign over his rights, most likely in MO he could not even do it WITH your permission. If he says it again, tell him there is no such thing ( unless you are remarried and your new partner wants to adopt) Or just ignore him. Sounds like he wants to get out of paying the money and hope to cheat you in some way with threats that are untrue