Deleting Entities from within MSCRM 3.0 is fairly staightforward but you need to keep the following things in mind:

• You can't delete system Entities.
• You can't delete an Entity if it is being referenced on a Form of another Entity. An error message will be displayed alerting you to the references to that Entity.

To accomplish this, you must perform the following steps:

1. Edit the form that contains the reference to the Entity that you wish to delete. ( This is usually a Lookup field produced by adding a Relationship between two Entities. )
2. Remove the Lookup field and save the Form.
3. Save the Entity.
4. Publish the Entity.
5. Select the Entity you wish to Delete and click the Delete button.
6. Repeat steps 1-5 until you actually delete the Entity.

• As a safety measure, select More Actions, then Publish All Customizations, so that you can be sure that the entire CRM system has been notified of any changes you have made.