There are global and individual settings:
You can disable the plugin, but be aware that you have to also delete all the notifications manually or you will get errors on people’s browsers. See separate Topic on this matter:
Uninstalling (or disabling!)
You can presently limit notifications when you Follow someone or they Follow you.
Switches all follow notifications on or off for all users.
If the global setting is switched ON, user gets discretion:
(all default: ON).