Our monthly maintenance has suddenly stopped deleting anonymous customers from the customer.dbo table. I need to remove these as its growing at a rate where we can no longer update the customer records from admin as its timing out. Does anyone have SQL script (I am trying to find the actual one that does this within the monthly maintenance too) that can remove these anon customers.

We use Paypal so there are customers within that table that have placed orders but whose IsRegistered field is set to 0 so these need to stay. It's simply those who have no email, is registered is set to 0, no password, first name, last name etc...