There are a couple of ways you can retrieve your Amazon Seller ID/Merchant ID/Merchant Token.
Option 1. Click HERE. This link will redirect you to your Seller Central account to log in. Once you log in, the next screen will be your Amazon ID.
Option 2. If you’d prefer to navigate your way through Seller Central, start by logging in. Click “Settings” in the upper right-hand corner, then “Account Info”. Under “Business Information” you’ll be able to click through to your “Merchant Token”.