Delete row from two sql tables that join together

Revision 3
There are two tables:

Table1 : UserID Name Job
Table2 : BookID Book Car UserID

I load these two tables in one wpf datagrid:

da.SelectCommand = new SqlCommand("select Table1.UserID, Table1.Name, Table1.Job, Table2.Book, Table2.Car from Table1 inner join Table2 on Table1.UserID = Table2.UserID");

How can delete a row from Table2 based on BookID?
thanks