Click the "Domains" tab on the left hand side bar to open a drop down menu.

Press "List Domains" on the newly opened menu.

This brings you to a List of all domains you have administrative power over. 

At the far right of each listed domain there is status indicator, in order to erase a domain it must be set to stop.

Select stop then wait a moment for a confirmation message to display above the domain list.

Once the confirmation message displays, 

click the status again then select erase from the menu.