The ``function to delete followers without blocking'' that Twitter was testing has been officially adopted by the web version of Twitter today.
On Twitter, you can unfollow someone from yourself, but the function to unfollow someone from the other person was not implemented. For that reason, the standard method of unfollowing someone without causing a stir was "broken" (blocking and then unblocking to unfollow) was the standard method, but it will be a little smoother in the future.
The method is OK by opening the web version of Twitter, searching for the other party from the follower list, and selecting "..." → "Delete this follower". Even if you delete it from your followers, the other person won't be notified, so you can silently say goodbye to people you don't like or don't want to find out about.
However, the deleted user can follow you again later, so be careful!