second hand version 1 switch...internal system storage issue

Hi there, just purchased a second hand version 1 switch. Fancied having a dabble at bit of customisation. Got atmosphere p and running no problem. The first thing done was to format the switch.
Only thing is after the format the system storage is only showing 10gb free space 0f the standard 32gb. Formatting several times shows the same results. After installing atmosphere i can gain access to system storage via Tinfoil. Tinfoil File Browser System:/save has many files within it varying in size example: 8000000000000000 1.8mb and many many others like this some with larger file sizes.

is it safe to delete these using within the browser? Is there a particular reason why when formatting the switch the storage volume does not change.

Many many thx

 

Ive also located 4 nand.bin files in the user folder on the internal storage. These equate to my missing storage. I tried to delete these with in the tinfoil browser but wasn't allowed to. Is there another way to delete files ftom within the internal storage.

Thxxagsin

 

After a littls more digging i think the previous owner had sxos and this is the emunand on my sytemstorage. All the nand bin files are in the users directory. Ive tried nx shell to delete the user folder but you can only use it on sd card.
There was also another program ..Kex full system file browser but when loading this it just freezes and you cant do anything.
Ive tried haku but after the reset it still showed the same size storage internally being 11gigs.
Are there any other tools that can return my missing storage.
Thx