How to delete a FOREIGN KEY constraint using a database diagram (Enterprise Manager)

To delete a FOREIGN KEY constraint using a database diagram

Open a database diagram.
Right click the relationship line that connects the foreign key table to the primary key table, and then click Delete Relationship from Database.

Note Deleting a relationship from a database diagram marks the related tables as modified in all diagrams in which they appear.

Creating and Modifying FOREIGN KEY Constraints	How to open a database diagram
Deleting a Relationship	Deleting a Table