To reset, after you delete the record, do a compact and repair and you should be able to create a new record with the same number as the one you just deleted.
This only goes back to the last record ie, it won't allow you to reuse numbers missing from a sequence where a later number is being used.
1,2,3,4,5 delete 5 and reuse but delete 2, sorry, not possible unless you delete 2,3 4,& 5.
test on a sample table.
Check the properties on your autonumber, I think there is a setting to put the start number.
You can also use Formatted number I understand.