In case of Hsn code wrongly select by a taxable person.
You can amend it.
Its ok. If some other HSN code is selected. Most probably after migration process gets over government will give proper chance to correct your hsn code. For more details: firstname.lastname@example.org.
After implementation of GST, There will be an option in GST portal to rectify or update informations provided earlier. There You can rectify HSN Thank you.
You can change it after GST is implement.