Thanks for letting us know you want to uninstall the Large Media add-on for your site. Would you please confirm you have read the following Support Guide?
If you have read that, please confirm you have backups of all files and that the site below is the correct one to remove Large Media from.
I checked this site:
Site name: elegant-poitras-87214a
API ID: 4fb362e3-baf1-4055-b71c-10e6df2d5d06
There is a Large Media instance there and I can remove that when you confirm. For the second site, there is no Large Media instance configured so I cannot remove Large Media from decanter-preview. (There is no Large Media to remove there.)
Please reply anytime and if there are question we will be happy to answer.