Google Calendar Alert Changes on itself

1. Go to Device Settings
2. Select Calendar (or Mail, Contacts, Calendars in iOS9 and below)
3. Scroll down to Default Alert Times
4. Set Alerts to None

If these are already set to "None", it's a setting of your Google Calendar: all newly created events will get a default alarm of 10 minutes. You can change this at the Google Calendar website under Settings.

1. Go to http://www.google.com/calendar
2. Log in with your username and password
3. When logged in, click on Settings
4. Next, click on Settings for Calendar
5. A new screen will open, click on Calendars
6. For each calendar, click on Alerts
7. Remove the default alert by clicking on Remove
8. Click on the Save button

If the above didn't solve your problem, check the following alert settings:

•  Week Calendar > settings > New events & templates > New event defaults > Default alert

It should be like this....