You maybe receiving notifications every time someone uses a PIN you created b/c you did not toggle off the "Notify about usage" in the Optional Items.
You can turn off notification by navigating to the "Visitor Access" icon and clicking on the 3 dots to the right of the PIN. (see below)
Then click Edit
Scroll down till you see Optional Items and toggle on to expand
Toggle off "Notify about usage"
Click Update Visitor Code
From this point forward you will not be notified when your visitor uses their code.