BB Curve :: Can't Delete Email Account On 9300

I've bought a Blackberry Curve 9300 a few weeks ago and I've added 3 e-mail accounts to it the same day to see how it works, it worked fine on the first day but on the next one it stopped working. Only then I created a BIS account - which TIM is my carrier -. Now the problem is: I can't delete these 3 accounts I've added earlier. I've tried to add them again trying to make it work properly, but I am unable to re-add them. On my BIS carrier website, It says that I've reached the maximum e-mail accounts.

How can I delete these e-mail accounts? I've tried the methods found on the web, like the one to "reconciliate"(?) the e-mail account option through wifi (on the phone). PS: My Blackberry is running a 6.0 bundle 2391 OS.