end of child support

My employer is enforcing child support by court order. My son (by the way I have not seen him since he was 3 years old - he is living in former communist country,and I had absolutely no rights as to see or visit him, just to pay and send presents!),will turn 18 in May this year.I would like to know how I can terminate the service of an assignment (child support); do I have to file Notice of motion at court or what should I do to stop child support when he turns 18?

I forgot to mention I live in CA and my son in Czech republic. Which law applies in this case? Do I have to pay past his 18, and how about if he would go to school for next 10-15 years?

I hate to be this way....but..since you live in calif. I would check to see if your child is even getting ANY of the support you have been paying...I am very bitter with calif. and belive they only care for money .. not the puplic that lives here!