How can I change the SKUs of my products?

You can create copy listing to change your SKUs there is one more way to change SKUs you have to remove your listing at least for 24 hours then when you recover the listing amazon will give you the option to change the SKU as per you want.

To change the SKU of your product, first try to stock out the already stored inventory at the Amazon warehouse. Then save the information for that ASIN like its ASIN, UPC, etc. and delete the listing. Then, relist your product with the same UPC and ASIN but a different SKU. Then you can change the SKU of that product.

You can not change your listing SKU and if somehow you change your listing SKU, it will make a new listing in your catalog and your stock in the Amazon warehouse will not be available for the new listing.
In short, to change the SKU, you will have to create a new listing.

Before deleting the listing, keep the listing’s details for that ASIN, including its ASIN, UPC, etc. Then, relist your product using a different SKU but the same UPC and ASIN. After that, you can modify the product’s SKU.

Once you have submitted your SKU then you cannot change your SKU until you can not delete the listing and create the listing on the same ASIN.