How do I delete an item from a batch using batch editor in SPM12 within MatLab?

I want to delete a number of items in a batch load in the batch editor window in SPM12 within MatLab. Specifically, I am trying to delete subjects from one condition in my study to re-run analyses so need to delete some of the 'subject' files from the batch pictured below. When I select the 'Edit' menu the option to 'delete item' is greyed out so I can't delete the items this way- there is an option in the 'Edit' menu to 'Clear Value' but this seems to empty the item/file rather than delete it. Maybe emptying the item is equivalent to deleting in terms of the outcome of the analysis but would like to find a way to do the latter!

Thanks