Janner

I have just had to go back to factory settings. My documents and photos were backed up to an external drive and so it was easy to restore them to my laptop using File History. However I now find that the items now appear both in One Drive and This PC. On both the individual files are mostly marked with a white cross in a red circle but some are shown with a white tick in a green circle. I have received an email saying that One Drive free space is full and that I need to purchase additional storage, If I try to delete an item from either One Drive or This PC it disappears from both. I do not want to use One Drive. How can I delete the files now held in it without also deleting them from This PC, and how can I stop this happening again. Any advice will be very welcome. As must be very obvious I am rather aged and computer illiterate.