Yes, this is possible. To do so, right-click the file you would like to delete within DayliteDocs. In the following contextual menu, click Move "File name" to the Recycle Bin. Click Yes to confirm.
It is also possible to select and delete multiple files at once.
Please note: to remove the deleted files for good, the Daylite Trash (Daylite menu bar -> Window -> Trash) needs to be emptied. As Daylite was not designed to handle large scale files deletions, please avoid to delete hundreds thousands of files at once due to performance reasons.