I've made a video demonstrating how I accidentally enabled the Android Oreo style multitasking cards, pretty cool as I hate the new Android P style.
the commands is:
adb shell pm uninstall -k --user 0 com.huawei.android.launcher
Ensure you have another launcher installed and enabled BEFORE removing the stock launcher.
Also note you will loose the stock gestures if you enable it, only the back command works.
So I had to overscan the screen to remove the Nav bar, as using immersive mode broke the lock screen.