Ah. That's not a separate cell. That's just the cell label. When you selected and deleted, you just deleted the text that was part of the cell label. You can configure the cell labels. Go to the options inspector and search for "celllabel". You can choose whether to show the cell labels at all, and you can choose several other options. You might be interested in the template option. You can adjust the template so that the label is less obtrusive.

Please provide sample code that produces the effect you're describing. Also, provide a visual of the output and describe what you want to change.