Q: How do I reset Exchange ActiveSync policies applied to my Windows 8 machine for Exchange mailboxes I've since removed?

A: Once Exchange ActiveSync (EAS) policies are applied to a machine, they remain even after the mailboxes that required the policies are removed. This is because you could have multiple mailboxes that required the policies. The good news is the policies can be reset using the following actions:

1. Open the desktop control panel (Start the desktop, then select the Settings charm and select Control Panel).
2. Open the User Accounts control panel applet.
3. Click the Reset Security Policies link in the left hand navigation menu at the bottom and click Reset Policies in the displayed dialog, as shown.
    
   EAS Reset Policies
4. The ActiveSync enforced policies have now been disabled.

Note that if you reset the policies and still have the mailboxes configured, within a day the Exchange server will notice you turned off their policy and ask you to enable it again to resume access to the mailbox.

You might want to also look at Tony Redmond's Exchange Unwashed blog--he's written a lot about EAS.