How to delete a quick entry purchase invoice that has not been allocated

SOLVED

I have accidentally entered a duplicate quick entry purchase invoice and need to delete it.  

Sage help says

1. From purchases, choose quick entries.  

2. Select the invoice or credit note you want to delete

3. Select the delete icon and save

Sadly step 3 doesn't work as there is no "delete" icon anywhere on the screen.

Does anyone know the answer to this?

The duplicate invoice is dated 6th December 2023, the correct invoice dated 12th December 2023 has been paid.

Could it be that the invoice has somehow been "allocated" as it is from last year?