Here's how to remove a follower using the new feature.
First, you'll need to be on the web version of Twitter, so don't use the app on your phone.
Go to your profile and click on "followers."
Scroll down to the person you want to soft block, then click the three vertical dots to the right-hand side of their name.
Select "remove this follower" - and that's it. This person will no longer see when you post or retweet things, and Twitter won't notify them that you've removed them.