This article covers 

Is it possible to disable the “Request Payment Method” email notification?
When is the “Request Payment Method” email notification sent?
How to edit the “Request Payment Method” email notification.

Solution
The Request payment method email is only triggered when you manually click on the "Request Payment Method" option on the Customer details page. Apart from this, the Subscription renewal reminders, Invalid payment methods email notifications have the Request/Update Payment Method button. 

You can still edit the contents of the email by clicking on the "Edit" option under Settings > Configure Chargebee > Email notifications > Standard Email> Request Payment Method Update

This will update the contents of the email globally for your site and the updated content will show up every time you use the "Request Payment method" option.

It is also possible to edit the email notification specifically for one customer. When you click on the "Request Payment method" option on the customer details page, you will see an “Edit” button, using which you can specifically edit the content of the email for this particular customer alone.

Related articles and Documentation
Request Payment Method