Need a wordpress expert to fix disk full issue

I have an ecommerce website for digital downloads. It was speed optmized recenty by another freelancer. Now I cant upload new products as it shows can't write to the disk.It shows disk full in cpanel as It is used 25 gb of space. Im sure there is nothing that much big im using in my website. I need someone to exactly figure out what the reason is and fix it from happening again. Attaching the cpanel screenshot.

Thanks