If you do not wish to use or see the Call phone feature in your Gmail chat list, you can disable. To do so:
- In the upper right-hand corner of Gmail, click the gear icon and then click Mail settings.
- Click the Chat tab.
- In the Call phone section, click Disable outbound voice calling.
- Click Save Changes.
The above steps only disable outbound calling in Gmail. If you have enabled Google Chat as a forwarding phone in Google Voice, you must disable it separately.