First I will explain a bit why they stay there even when you relist them; one of the functions of the unsold items screen is to account for fees related to listing that are not accounted for in sold items, if the item never sold. This information gets rolled into the totals of the reports.
As for your question, No, I dont think you disabled anything.
When you deleted the entries, how did you do it?
To safely delete entries:
Click the Full Screen button to reveal the row numbers
Right click the row number you want to delete, select delete.
It is possible you only partially deleted the entry if you did it another way, if that doesnt help you please contact me at
support@mycostpro.com so I can get some more details from you.