How to: Delete Relationships (Visual Database Tools)
Delete a relationship when you no longer want to relate columns in two related tables. When you redesign tables, it is often necessary to delete relationships and then recreate them after your new design is complete.
To delete a relationship
In Object Explorer, right-click the table involved in the relationship, and click Design.
The table opens in Table Designer.
From the Table Designer menu, click Relationships.
In the Foreign Key Relationships dialog box, select the relationship in the Selected Relationship list.
Click the Delete button.
When you delete a relationship, the relationship is deleted from the database when you save the table.