I specifically tested this on the Motorola Q9C, but I suspect that this will also work on the other Q models, as well as possibly any other phone running Windows Mobile 6.
1. From within the text messaging/email application, go to the menu, and choose “folders.”
2. Move down to the inbox, Highlight the inbox, but don’t select it.
3. Press the right softkey, which takes you into the menu.
4. Within the menu, you will find an option that says “clear all text messages.” Select this.
Give the phone a few seconds, and all the text messages in your inbox will be deleted. You can also do this with all the other folders. I hope someone else finds this as useful as I did. Until next time.