Your e-mail address will only be used for the process of generating the timestamp certificate, to send you the certificate, and to contact you in case of problems. As soon as we have sent you the certificate, your e-mail address will be removed from our servers.
(*) Actually it is quite difficult to remove files. The only thing the website does to "remove" your file is to depend on the PHP functionality to remove uploaded files from their temporary location, as soon as a PHP script finishes. We depend on our hosting provider to properly implement this PHP feature. Even then, "removing" a file usually does not remove the file contents from the hard disk.