I was living with a woman in 2004. She had a child in 2005 and a paternity test later that year proved that the child was mine (I had to get a court order to get her to agree to the test though). In 2008 she came to my home with her youngest child (not mine) and asked that I drop my rights to our son. She agreed to drop the child support if I did.
On jan 6, 2009 we both signed a noterized document stating the following.

I (My name) do hear by give up all right, both present and future to (our sons name). The child which was conceived with one (her name). I will not at any time in the future demonad custody, or interfere with decisions made for the well being of (our sons name). I gie up my right to any say in any choices that in any way concern (our sons name).

I (Her name) do hear by give up all right to financial support from (My name) on behalf of (our sons name). I will not make any legal, nonetary, or medical demands for (our sons name). I release (My name) from any and all parental responsibility and accept responsiability or (our sons name) to be solely mine.

Then we both signed and dated it including our social security numbers, then added his name and social security numbers for good measure. And it is noterized.
She is still charging me for child support and I want to know what my options are and if this document is in good legal standing. Can she be held in breach of contract and have to pay back the child support she has received from me since then?

Is she getting child support from you because she is getting welfare?

If she gets state aid, the state WILL go after the father for child support.

A notarized document doesn't mean diddly as far as rights and responsibilities to a child, you know. You MUST do ALL of that through the courts. And I know of absolutely no states that will allow someone to terminate parental rights to get out of child support.

Unless she re-marries and her new husband adopts, you're stuck with child support.

The GOOD news is that you haven't given up parental rights at all, and can go to court to have them enforced, including court-ordered visitations. This way she cannot prevent you from being involved in your child's life.

You DO care about your child and want the best for him, right?

Yah. I Didn't reallly think it was valid when I signed it, or I probably wouldn't have, but I knew it would confuse her if I suddenly took her to court, which I'm about to do. She did remarry, but I don't think he will want to adopt.

In my State.. if the child support was made in a Court of Law, then the child support is still in effect until a Court of Law says differently (stops the child support).

You & her, making a document, and signing it, won't stop Court appointed child support.

To stop your child support.. a Judge in a Court of Law must issue a court order that says it's stopped.. otherwise, your child support is continuing every second.

You might find this information helpful:
https://www.askmehelpdesk.com/family-law/signing-over-rights-read-first-116098.html

It's a sticky note posted to the top of this forum.

As noted, only a court can terminate rights. So the paper you signed is not legally binding unless a court ratifies it.

The thing you don't say is how support started in the first place. I assuming that she got an order for support after you got the paternity test. Did the court action you initiated include orders of custody, visitation and support or where there separate court actions?