Forgot My Passcode
The only option would be to delete your app and re-sintall it from the App Store (you will not be charged again if you use the same Apple ID you used to first purchase the app) to create a new password. But please keep in mind that if you delete the app all the data saved inside will be deleted as well.
Forgot passcode but have touch ID set up
this is what you can do:
1- enter the app with the touch id
2- export the data (see in the settings screen)
3- delete the app
4- reinstall it
5- set a new passcode
6- import the data back
* you must export your data before deleting the app or you will lose all your data. Please see the import/export feature in the app's settings for more info