How to Stop Twitter Auto-Follow
Auto-follow is a service offered by some third-party applications that allows your Twitter account to automatically follow people whether you are online or not. At the time of publication, Twitter only allows auto-follow to follow back people when they begin following you. Any other type of auto-follow is prohibited by Twitter. If you decide you want to stop automatically following people, you can simply revoke the application's access to your account using Twitter's Connection menu. This menu lists every applications that has access to your account, allowing you to revoke access to them at any time.
Open your Web browser and log into Twitter with your username and password. This will take you to your Twitter homepage.
Click your username on the top right of your Twitter homepage. A drop-down menu will appear. Click "Settings."
Click the "Connections" tab of the Settings page. This will give you a list of every third-party application that you have granted permission to access your Twitter account.
Scan the list of applications that have access to your account. Each entry will describe what the application. The entry will also tell you what type of access the application has: read-only, or read and write access.
Click the "Revoke Access" button beside any application you suspect is auto-following on your behalf.
Be careful not to revoke access for services you use. If you use Twitter for iPhone, or TweetDeck, revoking access will prevent you from using these applications until you grant them access again. You can grant them access to your account the next time you use the application by supplying them with your Twitter username and password.