1. Open your store database. You can do this in phpmyadmin (if you have one) or MySQL Workbench (if you have remote MySQL connections allowed) or in any software that allows you to browse a database.
2. Find table called eav_entity_type and open it.
3. In this table find row which has entity_type_code = order. Look at value in entity_type_id in that row and remember it, it's important. I will assume that order entity ID is 5.
4. Now find table called eav_entity_store in your database and open it.
5. If you already have made some orders you should see a row with entity_type_id = 5. If not - the table might be empty. If it's empty - I'd recommend you to create an order manually to auto-generate the row. You might also see multiple rows in that table, but you should only focus on entity_type_id = 5.
6. When you have the row with entity_type_id = 5 then you can modify increment_prefix and increment_last_id values in it. Delete value in increment_prefix (this will remove leading 1) and set increment_last_id to whatever you want. I'd recommend you to set the new value not lower than part without “10000000”, e.g. if it was 100000007 - set it to 7.
7. Now go back to table eav_entity_type, find the same row with entity_type_id = 5 and set increment_pad_length = 1 (this will remove zeros 0000000).

Try to place a new order and check what ID it will have.