For remapping your Asin you have to use the old listing all data and sku as well that’s how will be able to remap your Asin. but you can not remap your sku on the existing Listing. for that purpose you have to delete the listing and again make a new listing then you will have new SKU.
You have to permanently delete the listing and then relist it with a new SKU, most of the time deleting the listing from inventory tab will not lead to completely delete the listing from Amazon catalog so you firstly need to delete it and relist again.
You will need to create new SKUs for the products that you want to remap. These SKUs should be unique and cannot be used by any other products in your inventory. Once you have created the new SKUs, you will need to update the listing to map the new SKUs to the existing ASIN. After updating the listing with the new SKUs, you should see the new SKUs associated with the ASIN. Make sure to double-check that the remapping was successful.
For remapping on an existing amazon listing you have to delete the listing first and then upload it again with the new SKU but you have to be careful if you have the inventory in the warehouse the inventory won’t be shifted to your new SKUs even the ASIN will be the same.