How to delete in Event Receiver when I have got two lists

Question

In Items Adding Event I write on field item ID by (ID + 1), and then I gets a current one which are now adding. And then i must delete like in delete cascade all elements in corelate secound list. In the secound list there is a description of first list. How I can delete all lists on Events Receivers Items deleting. All elements bounded from the first, and secound list should be deleted. One record in first list and a lot of elements from secound list.