How to: Delete Primary Keys
Delete a primary key constraint when you want to remove the requirement for uniqueness for the values entered in a column or a combination or columns.
The dialog boxes and menu commands you see might differ from those described in Help depending on your active settings or edition. To change your settings, choose Import and Export Settings on the Tools menu. For more information, see Visual Studio Settings.
To delete a primary key constraint
In Server Explorer, select the table with the primary key, and from the Data menu click Open Table Definition.
The table opens in Table Designer.
In the table grid, right-click the row with the primary key and choose Remove Primary Key to toggle the setting from on to off.
To undo this action, close the table without saving the changes. Deleting a primary key cannot be undone without losing all other changes made to the table.
The constraint is deleted from the database when you save the table or diagram.