Customer Email already exist

[saasentrepreneur]

I'm currently integrating PSB into my SaaS so testing a good amount. I deleted all the test data (payments/invoices/customers) and am attempting to manually create a customer with a previously used email which gives me the error 'Email already exist.'

I saw in a previous forum thread (Customer is not created automatically) that the emails are unique so I was wondering how could I restore the customer account as it doesn't seem to let me create a new customer account for that email.