The text will be delivered to the user, and he/she will see that you've deleted the account making it impossible to add you or obtain information about you. However, if that user configured its privacy settings to allow messages only from friends, then the message will not be delivered regardless if you keep or delete your account. This is generally available for all these chat applications released nowadays (eg. WhatsApp, Viber, WeChat, Line, Tango, etc).
