Our web SDK saves a local storage item and a cookie to identify a user and there is also a push subscription sitting separately in the browser settings. These must both be cleared.
If you delete data but keep the push subscription, the next time the user opens the website they will be automatically subscribed to push notifications with the same token. To make a clean environment you need to delete both data and the push subscription in settings.
Details on removing your push subscription on mobile below:
Go to: Chrome > Site Settings -> Notifications or Click Site Settings from a notification in the notification center and then click Clear & Reset on the individual site settings screen
Clear & Reset on the site settings screen:
In Chrome Desktop go to Settings -> Show advanced settings -> Content settings -> Notifications