Go to eBay and sign in to your account
Open the buyer’s profile or any recent message from the buyer
Copy the buyer’s username
Go to Seller Hub or My eBay
Open Account settings
Select Site Preferences
Find Buyer requirements or Blocked buyer list
Add the buyer’s username to your blocked list
Save your changes
If needed, block the buyer from bidding or buying in your listing settings
Review your blocked list periodically and update it as needed