You don't need to.
You can't do this. You either protect your tweets and approve people to follow you or you unprotect your account and your tweets are viewable and anyone can follow you.
No, they can't tweet you.
Yes, anyone who is following you when your tweets are private can view them.
It may just take a while for it to take effect. If it still doesn't change then you should email the help team who should be able to change it for you.
The retweet will still exist.
If someone has blocked you on Twitter, you'll be able to send tweets to them, but it won't appear in their mentions. The only way they'd be able to see it if is they unblocked you to see it. They will be able to tweet you as normal, but they won't see what you tweet them.
No, it won't show up.
Anyone that was following you before you protected your account can still see your tweets/activity unless you block them or they unfollow you.Once your account is protected, only those people that you accept can follow you and view your Twitter activity.
No, Harry Styles did not delete his Twitter. He still has a Twitter and actively tweets. His Twitter username is @Harry_Styles.
Yes. Tweets will only disappear from your home page if the person blocks you.
The USA site may still have the Psych Hash tag killer walk through. The cast answered all the questions on Twitter.
You can protect your tweets but all of your followers will still be able to see the tweet and not just one specific person. To keep a message completely private then you should use the direct messaging option.