You can but, you'll lose the 15% initial deposit. Read below.
budsgunshop.com/layaway.php

Hi Adrian, unfortunately no. Items on a layaway cannot be changed once the 15% deposit has been received. If a layaway is cancelled prior to 90 days the 15% deposit will NOT be refunded.
budsgunshop.com/layaway.php

Hi Adrian and welcome. Yes but, you will need to contact Buds Customer Service to do so at 1-859-368-0371 9am-7pm EST Mon-Fri. or use the Blue Chat now button at the bottom right corner 9am to 7pm Mon-Fri. If they ask for a restock fee, ask them to waive it. Cheers and stay safe!