Yes, sure you can.
Mithi is a custodian of your data and not the owner.
You can use the Export functionality of Vaultastic to pull out your data. If the data size is very large, you have the option of receiving this via a physical medium, the AWS snowball. Please note that the export process is billable on a per GB basis, along with any services if you require and the use of the AWS snowball if required. The use of these resources is tracked by our billing system to be added to your monthly bill.
Once you cancel the service, you will not be able to access your data, and the data will be marked for automatic deletion by our systems.