The best solution is to install another notification manager and configure it to not show notifications:
$ sudo apt install dunst
This will exchange the current notification manager with the new one.
Now configure dunst to not show notifications:
$ cat<<ENDL > ~/.config/dunst/dunstrc [ignore] summary = "*" format = "" ENDL
Alternatively, you can tell it to suspend showing notifications instead of displaying them immediately. Dunst will queue them up while in suspended state.
$ killall -SIGUSR1 dunst
You can disable the suspended state with SIGUSR2, like so:
$ killall -SIGUSR2 dunst
Notifications are not a useful UI paradigm for me. They always happen to appear exactly where I just wanted to read/click something else. When I would have needed the information in the notification I am sure to miss it because I did not pay attention to the general area where the notification appears. Also, it can be very distracting at times.