If you would like to remove a dashboard you will need start in the given entity and click the gear icon next to the "Dashboards" section header as shown below:
From here, you will want to select the drop down arrow on the right hand side of the given dashboard. After you click the arrow, you will after the option to "Rename" or "Delete" the dashboard. Click "Delete" and you will be prompted to confirm this. An example of this is shown below:
Click Yes, and your dashboard will be removed.