I have heard about you can hide it in toribash options but I don't find it, how can I hide it?

You can't.

At least, it's no normal toribash option to hide your flag. You can hide some other of your details here tho: http://forum.toribash.com/profile.php?do=editprofile

If you want your flag to remain secret too you can download a vpn (most free ones aren't very good) and change your ip adress to anything but the country you are in right now.

Oh ok thanks, I will try that, hope this get closed (?

I'll close this for you. No problem.