Learn how to prevent tweets from a particular account from being displayed in your timeline. Rest assured you won't need to block or unfollow the user, you can simply mute his account instead.
When you mute an account on Twitter the following happens: Tweets from the muted account won't be displayed on your timeline and you won't receive push or SMS notifications when the user post new tweets.
How to mute a user
You can mute a user by visiting his profile summary. Sign-in to your Twitter account and click on the username displayed at the top of any tweet posted by the user. Click on the gear icon and then on Mute:
How to unmute a user
You can unmute any of your muted accounts by going to Settings > Muted accounts. Click on the red speaker icon next to the account(s) you want to unmute: