How to specify different FTP user in deployment credentials for each Azure Website?

I am trying to setup FTP access for the Azure website.I have added a user in the deployment credentials for an Azure website.Which is fine,but the same credentials are replicated to all the remaining websites in my subscription.
Is there any way to adding a user for only a specific website? Or Can we delete the user from a specific website?
How to specify different deployment users for each Azure website?