No, you would not be able to delete the text messages from online or from the computer using a usb cord. To troubleshoot your device to get it working properly, you can do a soft reset on the device. To perform a soft reset, leave your phone on , take the battery out for 10 to 15 seconds and replace battery into the device. Once you put the battery back into the device, dial *228 option 1. The last resort for troubleshooting your device will be performing a hard reset. A hard reset will remove everything from the device.