Extreme SSD 55AE is hidden and cannot be reformatted - help please!

Hello!

I bought my sister a 1TB SanDisk Extreme 55AE.

She uses a Windows laptop.

She managed to find the hidden file for her Apple iPhone backup that was taking up approx. 50GB of space on her laptop.

She moved that file over to her SSD to clear space.

It has now hidden the drive…

I can’t see it when it is plugged in, unless I also tick the box to View Hidden Items.

When I try to reformat the drive it says there is no drive there to reformat.

I was just going to try and clear the drive and start again… but I can’t seem to find any way to do that.

Any suggestions? Or do I need to give up…?