Firstly navigate to the diary tab
Next select an item tapping on the row you wish to edit or delete.
Now you can choose from the options of if you wish to edit or delete an item.
A secondary way to delete an item from anywhere with in the the app is use the standard Apple swipe to delete.
To do this simply do a quick swipe left to right over an item and a delete option is presented.
Selecting the delete option instantly deletes the item.