Select the option to "Protect my Tweets" under "Security and privacy" settings. Go to the profile of your unwanted follower and block them. This will make them unfollow you. If you want, you can then unblock them (or not).Dec 12, 2013 read more
Go to the profile of your unwanted follower and block them. This will make them unfollow you. If you want, you can then unblock them (or not). Just make sure to unprotect your tweets to make them public again. This won't stop someone from re-following you, but with any luck it'll be a while (or never) before they notice that they "accidentally" unfollowed you. read more