If you want to unfollow on twitch you need to do the following.
in to your account
Go to the person’s twitch link and click unfollow link. At the upper right area of the screen there is a heart-like button, and then click unfollow when it enlarges up.
Alternatively do the following;
Log in your account
Click “Following” tab it will bring you profiles.
Click the green heart button
Once clicked / unfollowed it will turn red.