Doesn't the LG Extravert have a full keyboard too? Access the menu, your messages, and delete them using the keyboard.
Page 14 of your user manual... http://www.manualspdf.com/lg-extravert-manual-user-guide-troubleshooting-english-spanish-verizon-wireless.html
I can imagine the irritation with not having a touch screen that works. The option from SuzyQ is accurate to delete messages using the physical keyboard. I would suggest also using the keyboard to calibrate your touch screen again so that it will function. http://bit.ly/Spfhav will show you how to calibrate again. Keep us posted if this works.
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