Voicemails that won't delete

Question

I bought this phone from a previous owner and there seems to be 2 voicemails linked to this phone that I cannot get rid of. I have trouble shot with my local AT&T dealer and without success the icons are still there. When I turn the phone on a banner comes up notifying me of the voicemails but when I go to view and delete them they won't. How do I make this go away or how can I find out if there is any new updated software to this phone. I have webt to the LG site and get no where. Please help