How to delete unsent message from google hangouts?

I accidentaly sent a confidental message to an incorrect contact. Fortunately, I could react in time, and I turned off my phone before it could be sent.

I opened my google hangout from the web, and I see that the message was not sent. (It was a big picture, whose upload was broken by the poweroff.)

However, now if I turn my phone on, the message will be sent.

I believe, my only way to delete the message, if

• I ban the phone from my home wifi,


• I remove the SIM card from it,


• I turn on the phone,


• I uninstall google hangouts,


• Re-enable my home wifi,


• Reinstall google hangouts.

However, doing these is problematic.

Does a quicker way exist for that?