How do I remove someone from my Friends list?
When you remove names from your Friends list, you are also given the option to move the person to your 'Blocked' list. If you would like to block someone from talking to you, tick the box next to 'Block this person' in the dialogue box that appears and click 'OK'.
Each time you add new contacts in Google Talk, they are also added to your Google Mail Contacts list and vice versa. Keep in mind that removing or blocking someone from your Google Talk Friends list does not affect your Google Mail Contacts list.