If you’ve created a Twitter account for your website for branding purposes and no longer maintaining that site and account on micro-blogging site, or joined Twitter for personal reasons and no longer using it, you better to close your account before it being fell into the hands of a wrong person. You need to deactivate your account first, after that, Twitter will delete it permanently within 30 days.
Closing a twitter account
1. Sign in to Twitter and visit account settings and click on Deactivate my account button at the bottom of the page.
2. Verify the reactivation information provided on the page, re-enter your password when prompted and click Deactivate account.
3. Twitter displays ‘your account is now deactivated’ message on the next page and reminds it will be permanently deleted in 30 days.
If you change your mind, you can reactivate your account by signing in before it being deleted by Twitter permanently.