If you have been given privileges to delete assets in an archive, you can select the files and open the Asset Information panel (keyboard shortcut T) where you find the Delete icon that looks like a trash can on the Information tab. Click it to delete the selected asset(s). You need to click it twice to confirm the delete operation.
Deleted assets will be removed from the archive and made unavailable, but will be retained for a short period of time before being permanently purged. If you have deleted files in error you need to contact Fotoware support ASAP to retrieve the files before they're permanently purged.
Tip: You can also delete selected assets by pressing Delete on your keyboard!