I did the same this one month back. All you have to do is the letter to USCIS telling them that your attorney will not represent your case in future and please mail all the communication directly to my registered home address.
Send this letter to address mentioned in I-797 Notice of Reciept of I-485 with acknowledgement return address card.
Look for my previous post related to this and you will find the sample letter as well.
Originally Posted by alex77
Folks, Please let me know if anyone knows where to send G-28 form if one wants to revoke attorney and be one's own representative?