You can safely delete your phone's local storage of the photo without losing the cloud backup. This means your photos are on a one-way will only send up to OneDrive as a photo backup. It is not a photo "sync", which would synchronize the photos between your phone and the cloud storage. Photo backup is just that.a backup of your phone's photos. This talk of photos and the cloud storage space of 1TB are related but not equal. Once you start using it, you'll get the hang of it quickly. No big issue to make back up before resetting device. Makes it easy to buy/replace phones, add devices, etc since all files are in the cloud. I save all my photos, music and other files on OneDrive so it's available to me at all times on any device as long as I have an internet connection. What ever you save on OneDrive will stay there no matter what you delete on your phone. Stuff that I don't access on a (more) regular basis. I do have a physical backup for my "archival" stuff too. For me, the cost of this convenience is worth the price I pay for, so I'm OK with it. Like I said, it is what you want.so YMMV.
I don't need to pre-install any software or hardware to make this happen. And yes, I do use my other devices to make quick updates to my files as I think of things - that is the convenience of cloud.I can do this on ANY machine / device that has an Internet connection. You also cannot add enough storage to tablets, phones or Chromebooks. This is all fine when they are desktops where you easily have extra drive bays - and of course they are all YOUR machines.but it is not easy to add extra HD storage to laptops, especially when they are work laptops.
Only the old archival stuff and large media goes on external hard drives and into offline storage. That's actually what I do, personally, for lots of my files. That's a good way to provide backup/redundancy, especially if they are geographically separated. You can put large HDs in your multiple computers and set up software to automatically sync your files between the computers.