How to hide users' personal profile to visitors?

Hi!
I'm the Admin of a forum here. 
What should I do to hide users' personal profile? How can I give them to have the possibility to choose to hide it or show it to visitors?

Thanx

Well its either a one way thing you can either have all profiles showing or none.

To change this option go to ACP --> Users and Groups --> Special Rights --> View the profile --> Members --> Save

So this is available for everyone, right? Not just for Admin?!
Thanx

All members can view each others profiles with this option.

Guests cannot.

ok! But this function to hide a profile, is available by every user? I mean: If a user wants to hide his profile to a guest, it has the power to do it, or it must ask me to hide his profile?!
thank you!

If you select members in that option.

Only Members will be able to see each others profiles.

Now say I visited your forum, I'd be a guest, I could not see your members profiles.

By selecting that option everyones' profile is unavailable to guests.

Members cannot choose if they want their profile to be hidden or not from guests. By you selecting that option in the admin panel they are automatically hidden from guests.

I hope you understand. If you have any questions let me know