Hello. My name is***** can help you with your question.
There are couple of ways that you can do this. One is to go into the settings and just remove the exchange account. If you are unable to do this through the email client app, you should be able to do it under your settings menu and then accounts. Just select the exchange account and remove. Alternatively, and what I would suggest doing if you want to get a fresh start with the device is just to go to settings and then backup restore and reset the device to the factory defaults. This will rewrite the factory image and allow you to input your security information, like your Google account, and you simply would not add the exchange account back. This would be the best long-term option, especially if the company has locked down any portions of the phone.