Cropping to a ratio means deciding, for the image's actual width and height, which dimension is the limiting one for the ratio you picked, then trimming evenly off the two opposite edges of whichever side is oversized. A landscape photo cropped to a 1:1 square loses width off both sides; a very wide photo cropped to a 4:5 portrait loses quite a lot.
This runs entirely in the codecs already built into your browser, so the crop happens in memory with no upload step and no server-side queue.
Your file is never uploaded, never queued on a server, and never deleted from one — because it was never there.