The Persistent Directory
When you format a new external hard drive or USB flash drive using the ext4 file system in Ubuntu, you will immediately notice a directory named lost+found sitting at the root of the drive. This folder is a standard feature of ext-based file systems, designed by the kernel to hold recovered file fragments in the event of a crash or sudden power loss during a write operation. However, for everyday file storage on removable media, this un-deletable folder can be visually annoying and confusing.
Reclaiming Your Drive Root
You cannot simply delete the lost+found directory; the file system will automatically recreate it, and attempting to remove it without root privileges will result in a permission error. If you want a completely clean external drive without this directory, the most practical solution is to format the drive using a file system that does not utilize a lost+found structure, such as exFAT or NTFS.
Alternatively, if you must use ext4, you can hide the directory using a simple file manager trick. Open your text editor and create an empty file named .hidden at the root of the external drive. Open the file and type lost+found on the first line. Save the file. The standard Ubuntu file manager (Nautilus) reads this dotfile and will no longer display the recovery directory in your normal view.