Undo Conversion to DNG?

Strange!

If you hover and 'let sit' the mouse cursor over a thumbnail image- Do you see a pop-up showing the Folder name?

You can also modify the Info shown on thumbnail borders by a [Right-Click] on the four locations on the top border edge, and set it to Folder.

"Does Extract tool work through Lightroom?"

No.

Run the Converter. Click on [Extract] button-

Bill,

not as complicated as it seems.. for the files you converted to DNG with the raw embedded use the tool to extract. Then you decide whether to keep the DNG or raw files.

It is wise to have xmp if you have raws files as an additional safety factor. 

Personally I write to xmp but convert to DNG to keep everything in one file as xmp us inside the DNG.

BTW DNG is not a space saver really. 

Going forward convert to DNG without including the raw and have the conversion delete the original, that is my way of doing it 👍

Thanks Jim for continuing the conversation (I have been away a while)

billt7.... 

Do not delete any files just yet!

As Jim says- you Extract the CR2 data from within the DNG file using the (standalone software) Adobe DNG Converter.  And this presumes that you did in fact 'Embed' the CR2s within the DNG. And you did use that option (Embed) right? (and you doubled the file size?)

Find the Download link for the Converter in this article- https://helpx.adobe.com/au/photoshop/digital-negative.html

If you converted those previously imported CR2 files using the menu within Lightroom, then the Lightroom only knows about DNG files that are shown in the Catalog.

So if you now Extract, and separate, the CR2 from the DNG- Lightroom still only knows about a DNG filetype and will NOT reference the CR2 filetype in the catalog. The problem now would be that the Develop history associated with the DNGs is not easily transferred to the extracted CR2 files.

If you Import the extracted CR2 files you now have BOTH a DNG and a CR2 showing in the Catalog. You can Copy&Paste Develop from the DNG to a CR2 one photo at a time, but you might be better with a plugin like "Syncomatic" to copy Develop work from the DNG to the CR2 files.

https://www.photographers-toolbox.com/products/jbeardsworth/syncomatic/

So "going back" is not easy unfortunately!

I only recently (July) began importing as DNG, so those files are only a DNG.  However,  I thought I could save storage by converting all of my previously imported CR2 files to DNG.  I unfortunately selected embed RAW file in DNG and the result was a CR2 and .xmp file plus the converted DNG for each image. I need to delete something, whether it's the DNG with embeded RAW file or the CR2 and .xmp file.  Where is EXTRACT and what will it do?  I'm running out of space in my 4-day old 8TB drive.

It's possible to work with your original raw files in Lightroom WITHOUT having XMP files. Just don't choose the option to write changes to XMP files, and all the changes will be written to the catalog. The key is to make sure your catalog is backed up on a regular basis. This is how I have utilized Lightroom Classic and formerly older versions of Lightroom now for years, and have not regretted it. No need to convert to DNG just to avoid XMP files. Just rely on maintaining a reliable Lightroom catalog.

I question why you have the RAW+XMP?  Is it the RAW version that you have imported into Lightroom and edited in Lr?

Do you have both versions as separate files  a RAW version and a DNG version?

If indeed you have the "DNG with raw embedded", then the Adobe Digital Negative Converter has an [Extract] function.

Consider carefully how your photos are indexed in Lightroom. If you imported them as DNG then you will find that Lightroom will not find ('Missing') your images when the proprietary RAWs (NEF CR2 etc) are 'extracted'.

Really we need a little more explanation of what you have, and how you created the DNGs.