Yahoo Messenger will be discontinued - After July 17, 2018 you will no longer be able to access Yahoo Messenger. Until the end of November 2018 you can download your messages and images to save to your computer or device

Can I reuse my deactivated Yahoo ID?

If your account has been discontinued for inactivity or by choice, you may be able to use the ID again. After the account is fully deactivated, anyone can select that ID to create a new Yahoo account. If it's not available, consider using a similar variation.