Linux AWS: Find And Delete All Files Securely So That No One Can Recover It Ever

I'm currently using Amazon EBS block level storage volumes for use with Amazon EC2 instances powered by Red Hat Enterprise Linux. This volume stores critical webapp and user data. We are moving out to another cloud provider. How do I find files such as *.logs, *.php, *.gz and few other file patterns and securely delete them so that no one can recover it ever?

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