To remove an application from your device, please use these steps below. Please note, in order to access an application on the Android Market you need to log into your Gmail account through your phone.
1. Press the Menu key.
2. Tap My Apps.
3. Navigate to and tap the application you would like to install.
5. Tap un-installing.
6. Tap Ok.
7. Tap the appropriate reason for uninstalling the selected application.
8. Tap Ok.
Also, here is a link for further assistance: http://support.vzw.com/simulator/HTC/thunderbolt/simulator.html#/MARKET_UNINSTALL