Is it possible to save on FOPNU server after deleting files from local folder. I know its a stupid question but I've seen many user have almost 100 TB data they could'nt possibly have such large storage.

So just asking

It has to be stored somewhere. You can buy hard disk drives for cheap(price per GB) compared to solid state drives. I bought a 1 TB HDD for about $35.

I think you have answered your own question, this is a decentralised network there is no server.

If you are that low on space get some cloud storage.

I hate to tell you this Guest but many of us have systems with reasonable sized drives, I myself have an array of 8X3 TB online drives and more offline as swappable inserts,I cant roll with them all online all the time because i am not well off, so for those that are you can see its trivial to exceed that number.