How do I remove the pin code from the Nexus 5?

[AC Question]

Hello,

I tried to access my Outlook email from work on my Nexus 5. I added the Exchange account under settings, but I was never able to access my Outlook email. After my phone screen timed out, it said I had to enter a pin code or I could only do emergency calls. Is there any way I can remove the pin code. It's really irritating that I have to enter the code to unlock my screen.

Thanks in advanced!