delete option for an e-mail address is dimmed

[wawad]

i have HTC TP2 WM6.5
i created both hotmail & outlook e-mail.
when i try to delete any of those two, the delete option is dimmed.
i try through two options:

1- Open up Mail
Click Menu, Tools, Options
Tap and hold the account i want to delete. >> it's dimmed.

2- mail, Menu, Accounts, Accounts, click Menu.
i have to tabs: Options & Delete. >> Delete Option is dimmed

please if anyone can help cause i dont want to make hard uninstall for the whole mobile.

wael