How to: Delete Foreign Key Relationships (Visual Database Tools)
Delete a foreign key constraint when you want to remove the requirement to enforce referential integrity.
In Object Explorer, right-click the table with the constraint, and click Design (Modify in SP1 or earlier).
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.
ConceptsFOREIGN KEY Constraints
Other ResourcesWorking with Constraints (Visual Database Tools)
Working with Relationships (Visual Database Tools)