But, that is the user folder for a deleted user. That's why it is there.
That folder is not associated with your active users, and (hopefully) has nothing inside that you don't want to delete.
But, that is why the deleted user folder is used, so you don't delete an account accidentally, without hope of retrieving something that you actually want to keep.
Look inside that Deleted User folder, and look through the files and documents that would be part of any user folder. Should not be anything in there that is not part of what you wanted to delete.
(You can sort the files by size, so you can quickly understand where the space is used (and which files are really large -- might be just some cache files, which can grow quite large very quickly. Cache files are almost always easy to trash when you come across files with cache in the name.
(You might find out that you never intended to delete that user, and you can move what appear to be important to you out of that deleted user folder, then drag the rest to the trash - empty the trash, so it's gone.
Let us know how it goes...