Clear your store (keychain, NSUserDefaults, ...)

Use new OAuthSwift object (or edit internal credential)

WKWebView (iOS9)

Delete cookies, session, etc...

let dataTypes = Set([WKWebsiteDataTypeCookies,
 WKWebsiteDataTypeLocalStorage, WKWebsiteDataTypeSessionStorage,
 WKWebsiteDataTypeWebSQLDatabases, WKWebsiteDataTypeIndexedDBDatabases])
WKWebsiteDataStore.defaultDataStore().removeDataOfTypes(dataTypes, modifiedSince: NSDate.distantPast(), completionHandler: {})

UIWebView, WebView

Delete cookies

let storage = NSHTTPCookieStorage.sharedHTTPCookieStorage()
if let cookies = storage.cookies {
    for cookie in cookies {
        storage.deleteCookie(cookie)
    }
}

SFSafariViewController or external web browser

Open the logout page of the provider