It's easy to get rid of a Dashboard page, text page, or rich text page that you no longer need.
To delete a Dashboard, text or rich text page:
In the menu bar on any application page, select Customize > Application and click the Pages tab.
Locate to the page you want to delete and click its Delete button.
In the confirmation prompt that appears, click Yes,
delete it.
Note: The delete option is not available for the Default Dashboard page. If you want to delete a page that you've designated as the default, make another page the default dashboard, and then delete the original page. You can also edit any dashboard page (including the default), or bypass the Default Dashboard by creating and customizing dashboard pages and then associating a page with each user role.