Twitter is perhaps the least cooperative of major services in allowing you to remotely log out. For iOS users, there simply isn’t anything that can be done remotely and access to the Twitter app must be revoked from your iOS device. Needless to say this is simply because Twitter is lazy.
To remotely log out a browser session or log out of the Twitter app for Android, you have to change your password. Head over to your account settings and under Password, reset your password. This will log you out of all Twitter sessions, including your Android app. iOS users are still without options.