I find myself answering this question regularly on the LTG forums so I thought I'd share it here too.
The plugin provided script to uninstall webroot always fails. The script will download the latest MSI and attempts to uninstall webroot using that. This (almost) always fails because it was (almost) never installed with the latest version. There is a further issue showing the error message which makes troubleshooting this more difficult. Only shows "T". After much digging you'll find its short for "This command is only available for products that are installed" and it actually performs nothing.
The fix? CWA runs as the SYSTEM account. If you send c:program fileswebrootwrsa.exe -uninstall from CWA (as shell in your script) there won't be any prompts and webroot should be gone within 5 to 10 seconds.
If this still fails then webroot had further issues and will need to be ripped out manually. Be sure to clear that wrdata folder (at c:programdatawrdata) or re-installing it will be another nightmare. I have modified the plugin-script for the installer also and I ensure it always clears that folder before installing anything.
On 64bit machines you may need to add the (x86) portion to the path above - this varies between machines so I run both on a 64bit machine.