Reset Facebook Token Reference - Facebook SDK 4.0

FBSDKLoginManager *logMeOut = [[FBSDKLoginManager alloc] init];
[logMeOut logOut];

or

[FBSDKAccessToken setCurrentAccessToken:nil];
[FBSDKProfile setCurrentProfile:nil];

to logout

Then when you login again, make sure to set:

login.loginBehavior = FBSDKLoginBehaviorWeb;

Like so:

FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
login.loginBehavior = FBSDKLoginBehaviorWeb;
[login logInWithReadPermissions:@[@"user_friends"] handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {
         etc...
}];

I found some info in the docs saying FBSDKLoginBehaviorWeb can be used for "kiosk" apps; which I guess are apps designed to have more than one person log into them routinely.

One thing to note, this login method creates a modal UIWebView which is set up for portrait mode. I'm not sure if its possible to change this yet.

Swift 2+ Simple Solution

FBSDKLoginManager().logOut()

Swift 5+ Simple Solution

LoginManager().logOut()