Please follow the steps provided below to connect the website to your other BlogVault account.

Step 1: Log in to the wp-admin of the website you are trying to add.

Step 2: Click on the installed BlogVault plugin on the corner of the website:

Step 3: Here you will see the email ID of the account that is connected to that particular website. Click Connect New Account to connect this website to your account.

Step 4: Enter the Email ID of the account you want to connect it to and click on Submit.

Doing this will redirect you to the BlogVault dashboard and the website will get connected to your BlogVault account.

You can also disconnect the previous account email ID as well if you need to. 
To Disconnect your account from your website, you can simply click on Disconnect.