The following steps will only delete your receipt picture. You will not delete the actual expense.
Step 1
Choose expense
Step 2
Tap Delete.
Inside the expense, the receipt options are found at the bottom.
If you don't see the options at the bottom, it is because the purchase is missing certain mandatory information (e.g. amount) which the app thinks you should add, and you will see a cross icon at the top right. Tap the cross, and you will see the Delete option at the bottom.
To delete an expense, see: Delete this expense.