Ok. So...
To answer your question, the transaction has already occurred, and there is no way to cancel or reverse it. The only real option that you have is try and find the person who owns this account (good luck with that) and kindly asking them to return your funds.

Unfortunately you openly said:

this account called @blockchain should be banned or something

Which shows that you believe that someone, who has done nothing wrong, should suffer for your mistake...this is the incorrect action to take, nevertheless, it is an action that cannot be taken, as you can't ban someone from Steemit.

My advice from now on is: If you are trying out a new wallet or something similar, and you are unsure of how to make a transaction, send a minuscule amount and make sure it works first. For example, next time send like 1.00 SBD and make sure you are doing the transaction correctly, once you see that you accomplished what you were trying to do, then you can send the other 80SBD.

I wish you good luck in trying to get your funds returned to you! We all make mistakes in the beginning.