Sorry, it is not possible.  Autonumbers handle themselves.

I'm not sure why it matters what the value of an autonumber field should be,
since the purpose of a unique identifier for a record that can be used to
join tables together. If the value matters, then you may want to consider a
different type of field.

If you are insistent on changing the seed value for your autonumber field,
though, you can run an insert query that sets the value of the field to 1
less than you want it to start with and then delete that record. For
example, if you want it to begin with 1001 then run the following query.

INSERT INTO YourTable (YourAutoNumberField)
VALUES (1000);