The files in your collection are copies of the original files, so you can remove them without fear of deleting the only copy. There are several methods for removing files and folders.

In general, all remove actions require you to first select the items to remove. You may select one or more files and directories using the techniques outlined here.

Once some files have been selected, click once on the Delete Button in the Control Button area. This immediately removes the selected items.

Another method is to make your selection and then press the [Delete] key on your keyboard to remove the files.

The final way to remove files uses the same drag and drop method you used to copy the files, except this time you drag from your collection down to the Delete Button. The button responds by becoming highlit, indicating that it is a valid drop target. Drop the selected items here and they will be removed from your collection.

If you can't remove a file, then most likely you are not meant to because it is read-only.