On JioCloud Android & IOS apps, go to the Security option (Settings -> Security). The ‘Security’ section will show a list of options. Tapping on ‘None’ or ‘Device lock’ will help you disable the Custom Passphrase.
On the JioCloud website, go to the Profile Page, by clicking on your username in the hamburger menu. From the Profile page, turn off the toggle for ‘Custom passphrase’. On turning off the toggle, you will be asked for your existing passphrase for security purposes. Once you enter the existing passphrase successfully, the passphrase would be disabled from all your devices.