The ISBN for a book loaded onto our website cannot be changed since it acts as the primary identifier for an eBook in our system. Database systems will not allow you to update the primary identifier in a table.
If you wish to alter your book's ISBN you will have to create a new entry for it on Kobo Writing Life, ensuring that the number is correct - and that it contains no dashes - and then delist the original entry with the incorrect ISBN.
N.B. ISBNs can only be added to our system if they contain NO DASHES.