The only directory that I would be confident saying could be deleted is the empty lost+found
directory. It would be recreated by fsck
if that tool repairs the filesystem and finds dangling inodes (see "What is the purpose of the lost+found folder in Linux and Unix?").
The other directories may be used or may be assumed exist by various system tools, applications and/or package managers on your system. In particular, deleting /home
, /mnt
, and /usr/local
(and possibly /media
) may well upset some software that relies on these directories being present. Both /mnt
and /media
(on Linux) are often used for mounting external drives, and /home
will contain your users' home directories (including your own).
A most general advice is to not blindly change things installed by default by your Linux distribution. The defaults (be it permissions on files or directories or various other configurations) have been tested by the distribution maintainers, and are supposed to work. Obviously, you may need to tweak things so that they suit your needs, but, you know, not blindly.
/mnt
is where things are mounted such as your hard drive,/home
is for you users (do not run a server with root as your only user!),/usr/*
is used for read-only user data, most of your utilities and third-party software will be kept in various places in/usr
or/opt
. It is better to practice good control over the access rights of these instead of deleting them. – kemotep Oct 28 '18 at 23:56