"Can you please let me know how to completely uninstall all web assist extensions?"
to completely uninstall extensions, recreate the users configuration folder as outlined in the adobe troubleshooting guide at step 12:
then open the extension manager, select each extension and remove it, then reinstall.
with data Bridge, there is a new install process. after installing the extension to the extension manager, open DW< and Open a PHP page to start the WebAssist installer.
when the webassist installer completes, restart Dreamweaver.