Is it prohibited to send Quranic verses by WhatsApp where people delete it after reading it?
Deleting electronic verses of the Qur'an is not considered a big deal according to multiple fatawa. An Ask Imam fatwa sums up why nicely:
When disposing of Quranic verses, the main objective is to protect the Quran from any form of disrespect. Since deleting Quranic files off of a storage device is not tantamount to disrespecting the Quran, it will be permissible to do so.
There is nothing wrong with sending Qur’aanic messages via e-mail or SMS. Rather this is the kind of deed for which a person will be rewarded ...
UAE news reports another fatwa encouraging it.
See also Is deleting the Qur'an from a computer prohibited? and Can I delete Qur'an recitation audio clips from my phone?, and Tamer Shlash's answer to Is it permissible to use a digital version of the Holy Quran?. (However, none of these posts give references to this particular question.)