A password reset would need to be done on the app. You're able to reset your password by selecting "forgot my password" on the 'sign in with email' page of the app.
You'll be asked to enter the email associated with your Flashfood account. You'll receive an email with a link to enter and confirm your new password (please check your spam/junk folder if you don't receive the link). You should then be able to access the app.