deactivate an account
i have already an account so i want to deactivate this account
The problem with that is that it does not deactivate the account. I have just created a new account, did one lesson and then deactivated the account before logging off. I then logged on with that deactivated username/password and I can still see my lessons and can still post messages to forums, as you can probably see from this message.
That is supposed to happen. You're deactivating your account, not deleting it. I've done that before. Why don't you try this:
Using one of your accounts, make a post on the other's profile. Then deactivate the former account. Login to your second account and see if your profile doesn't say "[deactivated user]:...........". If it shows the username instead, something is wrong and you better report it. If not, well, then we're good to go.