How do you delete 16 000 pages or start from scratch again [closed]

Someone hijacked my google search console for a while and he uploaded tons of sitemap with 16 000 website total.

I’d like to return to the way it was before, i asked for the sitemaps to be deleted but the pages are still there (it’s been 2 weeks already)

I was starting to ask myself if i couldn’t just start from scratch again and delete everything from google, is that possible or simply delete the right pages, and how

Thanks