I don't know that how you have bounded ListBox to database.
here is a good way to solve this problem. Imagine that our data is collected into a DataSet object named ds. define a DataTable like this:
DataTable dt = new DataTable();
dt = ds.Tables["your table name goes here"];
List1.DataSource = dt;
and when you want to delete from list1, you can delete data from dataTable object (dt) and automatically list1 is refreshed. Note that dt should be a global variable in class