You can find the Cancellation Report under Reports → Customers → Cancellation:

Date Range Type: Search by Cancel Date or Date Created This report will show you the amount of cancellations you have as well as well as the reason why:

You can choose a default date range or create a custom date range

You can also search by Campaign, Products, Mid, Affiliate, or Call Center:

Cancellation Reasons: The reason that was chosen on why a customer wanted to cancel.

This data can be exported by clicking Export CSV in the top right corner.

Cancellation Report Details

Cancel Reason: Reason provided by agent on Cancel Order Action
Total: Number per Cancel Reason