Remove a old issued DC Certificate from a W2K3 CA

I installed another Root-CA in the existing Forest. It is a W2K8R2 CA [enterprise].

I was trying to follow the step provided by Microsoft "How to demote a W2K3 CA" and I am at step 9 - Clean up DC

http://support.microsoft.com/kb/889250?wa=wsignin1.0

I found all the DC was issued with a new Cert from the old CA and it is not yet expire but I have already demoted the old CA.

I tried certutil -dcinfo deletebad...and it is not deleting it.

My questions are:

1) Is there a way to safely remove those certs from the old CA?

2) If I remove it, will that cause any issues? They are production servers.

Much appreciated.