Since there is not a way to just delete an email account from your phone and then re add it, the only thing that may resolve your issue may be a factory reset, which will delete all data from your phone and allow you to re establish your email account. This may reset any malfunction that your email account may have. You can do a factory reset by following these steps:
To reset your phone to factory settings and erase all
the data on your phone, touch Menu >Settings >Privacy > Factory data reset > Reset phone.