Trying to store files on My Cloud only (none on PC)

I’ve never had a personal server/NAS/cloud device before, I’ve just installed the My Cloud EX2 Ultra 8TB, and i’ve been able to sync files to it fine and access them via my phone and TV with no issue.
The problem which I can’t seem to find an answer to is, why are the files still stored on my PC? I’ve synced nearly 50GB of data to the My Cloud, and it was preventing me form adding anymore - I’ve since worked out this is because the My Cloud folder on my PC also had the 50GB of files, and was out of space not the EX2.

How do i upload the files to the EX2 without also having to keep them on my PC - I mean there’s 8TB of storage space in there, i’m not looking for a back up, i’m looking for storage.

I think what I’ve been looking for is mapping the drive to my PC.
https://support-en.wd.com/app/answers/detail/a_id/25436#subject2
However after completing this, when I’ve tried to copy files over it says that the drive cannot be located

ok, i’ve solved that too now. I couldn’t add files in to the new mapped drive for whatever reason, but I can add them directly to the network location - which also includes all the folders I have setup in the EX2. So once the NAS IP location is visible in the network list of Windows File Explorer, I can just pin the relevant locations to quick access to continue to use them.
This has removed all the files from my PC, and stored them on the EX2.

I mean seriously it’s like they’ve purposely made the device as convoluted as possible, especially when you consider out of the box the set up instructions are 3 images - plug in, wait for the lights to be solid, and go to mycloud.com/setup - this gives me no information about how anything works or where to find the manual - even then it’s taken me nearly 24 hours to actually track down what it was I wanted to do.