Lightroom CC backup your images on Cloud, but the those images are deleted from cloud they cannot be recovered. I would recommend you to add you vote to this discussion Lightroom CC: "Trash" Functionality | Photoshop Family Customer Community to let our developers know that a "trash" functionality would be great for recovering recently deleted images from Lightroom CC.
But even this question should be a reminder and a prompt to have at least 2 local backup of any file you don't want to ever lose!
Classic workflow here:
Connect Camera or Card to computer then copy files to a local drive using finder/explorer (NOT using Lr)
At this point I have 2 copies - 1 on a drive and 1 on a card
Then, in Lr Classic I Import from the drive using 'Copy as DNG'
Then I take both the DNG copies and the originals on the drive and back them up to another drive.
In Lr Classic, I then 'work on' the dng files. I also backup the catalog with every exit from Lr.
If I then want some of the images on 'the cloud', so be it. No worry about losing originals.
CC (cloud) workflow:
Shoot with mobile device (iPhone X here) using either of or a combination of the Lr camera or device camera.
Either way the files are sent to the cloud.
Images are then viewable via Apple TV, Mobile Device, Lr CC Web and Lr CC desktop.
Images can then be 'worked on' (developed) using Lr Mobile (or any other compatible photo app), Lr CC Web and/or Lr CC desktop.
What I DON'T do is try to get files from the cloud into Lr Classic using sync.
If I want (and to date I haven't) to use Lr Classic on images that are in the cloud, I bring them to a local drive using either Web or Desktop version. Then Import them into Classic using only ADD.
Many, many posts here from folks trying to use Lr CC and Lr Classic to manage synced libraries. Usually (more times than not) it causes a mess.