Switching from one Twitter ID to another is pretty easy.
You open your Twitter account settings, try a username that’s not taken and if you find one, hit the Save button.
What happens when you change your Twitter username?
Twitter handles the “username” transition pretty smartly. It won’t affect your existing follower count, your direct messages and the old tweets will be preserved and you’ll continue to be part of the same Twitter lists as before.
What’s the problem then?
Let’s say your original Twitter handle was @badguy that you later changed to @goodguy. Twitter will automatically shift your existing friends and followers to the new ID (@goodguy) but the search engines will still hold your old handle (@badguy) in their index for some time.
That means if people are searching for your Twitter account on Google, they may reach your old profile page and that will return a 404 as you moved to another alias. Therefore, when changing your Twitter username, immediately reserve the old one before anyone else can claim it.
Changing Twitter Handles the Right Way
Step 1: Go to your Twitter account settings and change the username from badguy to goodguy.
Step 2: Log out of Twitter immediately and create another account (you may use the same email address).
Step 3: Use badguy as the handle for your new Twitter account and set the profile URL to twitter.com/goodguy. In the description, you can say – “this account has moved, please follow @goodguy instead.” You can even post a new tweet with the same message.
Now if people stumble upon your old Twitter page through search engines or through links on other web pages, they can still find and follow you on your new profile. For more tricks, check the Twitter guide.