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 let us know which site to remove Large Media from. To identify the site, you can send us the site subdomain, API ID (the id not the key), or a link to the site (whichever you prefer).
Once we know which site, we’ll reply soon to confirm the add-on has been uninstalled.
Please let us know if there are any questions and, if not, please tell us the site to do this for.