How to: Delete Unique Constraints (Visual Database Tools)
Delete a unique constraint when you want to remove the requirement for uniqueness for values entered in the column or combination of columns included in the constraint expression.
To delete a unique constraint
In Object Explorer, right-click the table with the unique constraint, and click Design (Modify in SP1 or earlier). The table opens in Table Designer.
From the Table Designer menu, click Indexes/Keys.
In the Indexes/Keys dialog box, select the unique key in the Selected Primary/Unique Key and Index list.
Click Delete.
The constraint is removed from the database when you save the table.
See Also
Other Resources
Working with Constraints (Visual Database Tools)
Working with Keys (Visual Database Tools)
Indexes/Keys Dialog Box (Visual Database Tools)