Question about WPF C # CRUD Application

Question

Hello, I am writing a WPF application of C # but I got to EDIT and DELETE. I have reached the point where I need to EDIT or DELETE. Can you help me with advice on how to finish my code I use C #, SQL Server, 2014 Management Studio, Code First models. Two tables that are related. My wish is to remove the line that already exists or to make it EDIT. Thank you in advance. I use the code that is written here.