In the US, to talk about instantly canceling a transaction in a store we usually use the verb "void."I would say, "Excuse me, I scanned one of my items twice. Could you please void it out for me?"

I have done this before, and I have said this in the past. Simple "I scanned this twice." (The will automatically know what to do because I am sure it happens a lot.) More polite "Excuse me. I scanned this twice." More polite and more detailed. "Excuse me. I accidentally scanned this item twice. Could you help me?" The technical word is "void". "Could you help me void an item I double scanned/scanned twice/scanned two times?"

If you work in a shop in the UK, the correct verb is 'void'. You could also say remove, delete, cancel - all would be understood. However, to be honest, in that situation, I wouldn't use any of them. I'd just say, "Excuse me. Could you help me? I've accidentally scanned this twice." I wouldn't feel the need to say anything. It will be clear what needs to be done.

It's correct. 👏