You can turn off digests from your Notifications settings page:
From here, you'll be able to disable/enable reminders, digests, submissions and other notifications that are delivered via email or chat.
Simply uncheck the option to disable.
You may only want to receive email reminder notifications, or only chat notifications. If that is the case, click on the Custom link for the "Remind me when it's time to submit a standup or check-in" setting and deselect Email or Chat depending on the notification you'd like to disable.
Note: Admins of check-ins or standups have the ability to disable individual customization of notifications. In this case, you'll need the admin to modify the check-in settings.