mxf workflow - delete original media created in FCPX

I'm sure there's a thread for this already but I just couldn't find it.

I have material shot on Sony FS7 and I copied the whole mxf-folder structure to an external hard drive.
When I import in FCPX I cannot choose "Leave in place" ( I understand that is a good thing so I don't delete original media by mistake). So I import and create optimized media. FCPX then creates both Optimized ProRes files and new originals with a mov. wrapping.

So my question is: Can I delete the originals created by FCPX and only work with the ProRes, to free up disk space, and if so, how is the best way to do it? From finder window or is there a way to do it from FCPX?
I just assume that it's better to edit with the ProRes than the originals in mov. wrapping.

I have saved my originals (the mxf-folder structure) on an additional external hard drive.

If you don't "Leave In Place" you don't need to Optimize. I'd do one or the other, personally.

I'm not sure what happens if you delete the Optimized vs Original. I assume FCPX will simply use which ever is still there.

Duplicate the Library, use the duplicate as a test subject. Delete the Original folder, launch FCPX and see what happens. I'd be interested to know.

There is a way to delete Optimized and Proxies, I've File > "Delete Generated xxx Files." The idea is save the originals, because Optimized and Proxy can always be regenerated easily. And usually the originals are more compressed and will take up less drive space.

Thank you for reply,

I have a large material for a feature length documentary, which makes it a bit difficult to test - but I guess I can make a new smaller Library and see what happens if I delete the originals. I will let you know.

Since it's a large project I thought it best to leave all material outside the Library, directing it to a folder on external drive. And I just assumed it's better for the performance to use the optimized media and not the compressed originals.

Question:
The original files created by FCPX, are they just copies of the mxf-files from the camera but with a mov. wrapper?
If so, does that mean that I could delete the mxf-folder structure from the camera card?

FYI
So I did a test.

In a new Library I imported a file from the camera card. From the Import Window I directed the original to a folder outside the Library and ticked the "Create Optimized Media" box.

So after import I have both an Optimized and an Original-file (in two separate folders) created by FCPX outside the Library.
I then deleted the folder with the original file.

In FCPX the clip is still playing but in the inspector, under the "Available Media Representations" there's no sign of Optimized Media and the Original is now marked red.

When I click "Reveal in Finder" in the Inspector Window nothing happens, but when I click "Reveal In Finder" on the clip itself it directs me to an alias inside the Library, in the Original Media-folder there.
I don't know if this alias points to the optimized file outside the Library, but it seems that this is not the way it should be done.