How to remove "Invalid receipt"

I have question hopefully your team can help and support me..
How to remove word Invalid receipt? Where setting should i adjust?

This is because the receipt does not have the receipt number.

You can add the receipt number (1) or use your own receipt template (2):

1) Receipt number settings:

In mobile APP: Menu->Settings->Company settings->Receipt numbering.

2)If you don't want to use receipt numbering, you can setup your own receipt template:

In mobile APP: Menu->Settings->Company settings->Custom receipt template.

In Elementary POS Office please remove this variable: {validity_info}.