Deleting images in Lightroom

LIghtroom is a totally different type of application from the traditional photo editing applications.

I suggest you take about 10 photos - RAWS - like CR2, or NEF or whatever your camera shoots.

Then launch LR holding down the OPtion or ALt key. That opens a window which asks you to select a "catalog".

You click "create NEW catalog," name it something like "TEST" .

THEN BEFORE YOU DO ANYTHING ELSE, watch some of the training videos from Adobe and then "try" the steps from the videos with your TEST catalog.  

I recommend NOT just starting with Lighroom with all your photos and hoping to figure it out along the way! Use the TEST catalog and photos, and learn where and how LR imports and exports, and where to store your files and folders.

Lightroom Classic Get Started course

https://helpx.adobe.com/lightroom-classic/tutorials.html

I'm kind of freaking out that I can't delete whole batches of photos and that copies of everything are kept in an "all photos" folder.

Delete the photos from the "All Photographs" view. Click on one photo, ctrl-click on other photos you want to delete, then delete them. (Or click on one photo, then shift-click on the last photo of interest in sequence, to select and contiguous sequence, then delete them)

You may want to spend some time learning about how Lightroom Classic works (instead of trying to figure it out yourself). Please download and read the free beginners e-book for Lightroom Classic at lightroomqueen.com.

The first point to make about Lightroom Classic, is that the same image may / may not appear in many Collections but this is unrelated to it also appearing in a particular Folder. Each Collection is independent of the others, and independent of the Folders too. No longer wanting to see a given image within one Collection, does not necessarily mean you no longer want to see it anywhere else. So deleting an image from this Collection, just removes its membership there. It does not delete it altogether from the Library. A bit like saying of a real book in a library: this one is no longer our Book of the Month - it is just losing the assignment of a particular virtual attribute; it isn't being physically thrown on a fire.

So far as "really deleting", yes you can do this - however there is an important distinction between Remove (file remains in its physical storage, but no longer appears in this Catalog) and Delete from Disk ( file destroyed as well as no longer appearing in this Catalog). Lightroom for safety protects you from the accidental bulk deletion / removal of a lot of images in one go.

A preferred method is provided: you can mark images as deletion candidates, with the Reject flag (X key shortcut). Such images can be set to hide themselves straight away from a given Collection or Folder, dynamically, by setting a view filter. Also you can go to 'all photos', filter to ONLY show images marked for deletion, and double-check that there are no images in there that you would like to retain. But rejected images can then be cleared from the whole Catalog - either just Removing, or else also Deleting from Disk - as these instructions

Please confirm which version of Lightroom you're actually using (i.e. Lightroom Desktop or Lightroom Classic). To help, the screenshots below show Lr Classic on left and Lr Desktop on the right.

Both versions allow deletion of mutiple images to trash, although the method and number of steps required differs slightly.