Running Out Of Disk Space

A local disk on my computer is running out of space and Windows10 keeps popping this notice on my desktop. It's an actual "clone drive" which was installed from a previous machine onto this year and a half old computer, after my previous operating system began fragmenting (Windows XP Pro) and Windows was no longer offering updates. Here is my question, should I just let the disk get full? I'm only using it as a clone and my other disk (C has ample space left. See screenshot that keeps appearing

 

What is the point of the drive? I mean, if the content on it is a cloned OS that you no longer use, why not just extract whatever information you need to keep, format it, and use it for something useful?

 

When my last computer's operating system was fragmenting, my tech guy indicated it would be a good idea to upload all files onto his on-site server and upload them to the new drive on new machine, I.e. acting as my clone drive and the new machine (being all SSD) had a new drive to begin adding new files, invoices etc. to (use it for my business), so basically the point of that cloned drive is to preserve all existing folders and files and additional content since they are of great value to me....older images I worked on in Photoshop and saved as raw image files and so forth.
But the basis of my question is whether this should concern me (running out of space) since I also have the other C drive I'm working on + I do have automatic daily backups through iDrive. Could that drive be "compressed"? Or basically, how to turn of those notices that Windows 10 keeps popping on my screen?

 

My point was mostly: is ALL of the content on drive E: actual data? Or is there system files, left-over from the earlier installation? I dunno about the notifications, I've never had a problem with disk-space on Windows 10. I would assume it's possible. A quick Google-search gave me this: http://www.thewindowsclub.com/faq-l...on-or-warning-in-windows-7-how-to-disable-etc

 

Hello,

As per your provided information regarding Clone OS, if it is of Windows XP Pro. Then you can delete it and re create it for your usage as storage space. Because Windows XP is closed by Microsoft. Usually clone will be of image for the system recovery which is for factory reset.
If you feel it contains something else you better extract it and copy some where else.