Sean is absolutely correct - there is no easy way to do that in Access, and in general you shouldn't need to. Access treats autonumber fields as something the user cannot edit. The theory is that their only purpose is to ensure uniqueness.

That said, if you really have to do that, you can copy the autonumber contents into a new Long Integer field that is not an autonumber. Then you delete the autonumber field from your table, add the record that you want and assign it the missing number in the sequence, and finally change the design of the new field to be an autonumber. Then rename the field to be the same as the field you deleted.

If you do that very often you will decide it's a real pain. Alternatives - never allow a record to be deleted, and use a logical delete instead, or move your tables (and some of your fundamental queries) to a SQL Server back-end.