Be very careful! Undergoing the following procedure without knowing all 12 words of your wallet's passphrase will result in the complete loss of your wallet and it's contents. If you do not have or do not know your 12 words, do not, by any chance, proceed with the following procedure.
To reset your password, you will need to uninstall your app and then reinstall it once again. Once done, open the app and select the "Restore" option. After inserting your 12 words, you will be able to set a new password for your app.