Share your experience!
I have a horrible feeling that this is another major glitch with this phone.
I had to reinstall the software on my phone (a problem for another thread) so restored the messages from backup (third party app as none included), and something went wrong and there are duplicates of about half my messages, and they are not in order!. I decided to start again and delete all the messages and redo the restore, but this is has been going on for about two hours.
Finally convinced that the phone has just crashed (again), I decided to stop the app, restart it and, lo and behold, none of the messages have been deleted! What has the phone been doign for the last two hours?
Unfortunately it's not possible by default.
But if you like to delete all SMS from your phone, open messaging > press and hold on one conversation > press on '1 selected > mark all > press the trash can in the upper right corner.
Goto setting>apps>all>messaging clear cache and data
It takes so much if you have that many.You could try with myphone explorer,see it that works better.But it should do it,even if it freezes.
You need to use your PC with myphone explorer,see if that speeds up.