Ability to remove invoice me within time limit

If you are operating in the UK, it's a legal requirement to provide an invoice for any Product or Service sold (regardless of timeframe).

That being said, you can choose to send invoices manually in Tools > Options > General, by selecting the option labelled 'Generate Invoice number only when manually set to despatched or when a non tangible order takes place or by selecting the option to generate an invoice number in the sales manager'.

Ahh yes, I see what you mean.

There may well be a way to rig it to do this, though it's certainly not something that RomanCart supports by default. Because of this, I'm afraid to say that it's not something that we can really advise on, as payment systems are both delicate and critical. We wouldn't want to mess with it if it's working as intended.

Somebody else may have an idea for this, though I'd be very cautious about jury-rigging an unintended feature into the payment system.