Cannot uninstall an app from adb
Do you have to uninstall it from adb? If you have a rooted phone you can remove it from the device itself. There are a lot of apps that you can do this that are in the playstore. I personally use " system app remover (ROOT)". Just search for the app name and uninstall it.

PS: Did you try ading "su" at the begining of the command to use root?