Assume that you are having some set of rows in a table, and you are deleting those rows and willing to add new rows. In this scenario, the autonumber column of the new rows will not be restarted. They will continue from previous set of rows.
If you want to reset or restart the autonumber column you can follow any one of below approach.
After deleting the old rows, we can click Tools->Database Utilities->Compact and Repair.. for reseting the autonumber column.
Or alternatively, after deleting the old rows in a table we can copy and paste the table as a new table with "structure only" option.