On this page, underneath the artwork, you should see a button that looks like a pencil. That should let you replace the image file.

I forgot to modify the ratio when exporting the image, but I didn't see the button for modification anywhere.So how do I delete it?

Hello, as Pheno said; please submit it unscaled for it to be added to the gallery. Thank you!

This is a very frank and straightforward depiction of suicidality, and I think you've got a good control of pixels. But I don't think this is going to make it into the PJ gallery scaled-up like this. PJ has a zoom function built into the website, so users should submit their works at native resolution.