Calendar alerts are task reminders and can be managed within Salesforce. Review the Salesforce Help & Training article Enable or disable pop-up reminders for Tasks and Events.
If you have the Gmail/Outlook configuration, you can manage your task reminders within your email. Review the Salesforce Help & Training video Outlook and Gmail Integration on Desktop.
You can manage some of the alerts from your Account Profile:
Note: Administrators determine all other notifications that are sent.