Improvement of delete method
A few quick remarks:


In your second using statement, you declare a SqlCommand variable named cmdDelete. In the body of that using statement, however, you call ExecuteNonQuery on a variable named deletePolicyFromTdm. I don't see a declaration for deletePolicyFromTdm in your code, so I wonder if it should be cmdDelete instead.
I'm not sure where testNumber is coming from, but your approach potentially opens the door for SQL injection. I recommend defining it as a parameterized query (e.g. DELETE FROM table WHERE TestNumber = @TestNumber); it's a very small amount of work and will be one less thing to do when you switch to a sproc later.
Your brace style is not consistent. The braces following using are on the same line; the brace following try are on a separate line.