To delete you staging site using BlogVault:

Step 1: Go to BlogVault website and sign up using your email ID. 

Step 2: On the BlogVault site listing page, select the website of your choice.

Step 3: It'll take you to the Site Detail page. In this page, click Add Staging Site. 

Step 4: Click on Delete Staging.

Step 5: It will popup a confirmation page. Click on Yes to confirm.