Within the app, in the bottom tabs, tap on "..." to go to the More page. Select "Settings" and scroll down. You will find a section called "App Data" and the option to "Delete all My Cases".
Within the app, in the bottom tabs, tap on the last one to go to the Resources page. On the top-right tap the gear icon to go to the Settings page. Here you will find the "App Data" section and the option to "Delete All".