Migrate a customer account from one website to another in Magento.

Let’s say you have multiple websites within one Magento system and you want to transfer a customer from one website to another, so that this customer can no longer sign in to website 1 but able to sign in to website 2. To accomplish this, all you have to do is to change the website_id in the customer_entity table for the customer you want to transfer. For example, to transfer a customer whose entity_id=112233 from website 1 with website_id=1 and store_id=1 to website 2 with website_id=2 and store_id=2, the query below will do the job.

UPDATE `customer_entity` 
SET `website_id`='2', `store_id`='2' 
WHERE `entity_id`='112233';