See How to Determine Which Version of Plesk Control Panel is Installed on a Server to know which set of directions to follow.

Plesk 12.5

1. Log in to your Plesk Control Panel.
2. In the My Subscriptions section on the Home page, click on the [Subscription] you want to manage.
3. Click on the Websites & Domains tab.
4. On the right side of the page, click on Databases.
5. Click Remove Database option under the database name

1. Log in to your Plesk Control Panel.
2. In the My Subscriptions section on the Home page, click on the [Subscription] you want to manage.
3. Click on the Websites & Domains tab.
4. On the right side of the page, click on Databases.
5. Check the checkbox next to the database you want to delete.
6. Click the Remove button.
7. Click Yes in the pop up box to confirm.

1. Log in to your Plesk Control Panel.
2. In the My Subscriptions section on the Home page, click on the [Subscription] you want to manage. (If the correct domain isn't listed, choose it from the drop down menu in the upper right.)
3. Click on the Websites & Domains tab.
4. Click on Databases.
5. Check the box next to the database you want to delete.
6. Click the Remove button.
7. Click Yes in the pop up box to confirm.

1. Log in to your Plesk Control Panel.
2. Click on Domains and the [Domain] you want to manage.
3. Click on Databases.
4. Check the box next to the database you want to delete.
5. Click the Remove button.
6. Check the Confirm Removal button.
7. Click OK.