Delete local original on iPad

I’ve used LRCC on my desktop to put a large collection of original files (RAW, DNG,TIFF, JPEG, the usual mixture. I've then synced  to my iPad copy of LRCC but told it to only download smart previews. However, for some very large files that I sometimes want to see at 1:1 on screen I sometimes select ‘Download Original‘.

However, having done that, I often want later to delete that local original from my iPad because it might be several hundred MB and I don’t want to clog my iPad memory.

So how can I do this? Because if it’s not possible it will eventually be a huge iPad memory hog... and at the moment, deleting the file from everywhere seems the only way to do it, but I’m not ever going to do that because I want to keep the original in the cloud.

Thanks in advance.