1. From the main dashboard select "Contacts" from the client's drop-down box. 

2. In the next screen, you can search by account (purple arrow) or contact name (blue arrow). Once you have searched for the contact you want to select click on their name (red arrow).

3. After clicking on the contact you want to edit you can change any or all information here. You can also make the contact "inactive". Make sure to hit submit once you are done editing.