How do I open a folder as root?

To open the folder as root in the grapical file manager, run the following command:

gksu nautilus /etc/apt/

If you wish to do your operations from the command line, the following command enters the intended directory and makes you root. However, you would be better off using the first method above.

cd /etc/apt; sudo -i

To install Open-as-Administrator in Ubuntu open Terminal (Press Ctrl+Alt+T) and copy the following commands in the terminal:

sudo add-apt-repository ppa:noobslab/apps
sudo apt-get update
sudo apt-get install open-as-administrator

After installation type this command to restart Nautilus:

nautilus -q

Reboot

Ubuntu 16.04

sudo apt-get install -y nautilus-admin

Then

nautilus -q

Nah ! do a simple thing first. Create a custom file manager. Its easy.

Here how you can do it:

First open gedit and paste all these:

[Desktop Entry]
Name=Nautilus
Comment=Browse the filesystem with administrator rights
Exec=gksudo nautilus
Icon=file-manager
Terminal=false
Type=Application
Categories=Application;System;

Now save the file as Nautilus.desktop on your desktop.

(desktop is the file extension).

Now Open:

   /home/your user name/.local/share/applications

and cut/paste Nautilus.desktop file into there.

Now open dash and search for "Nautilus". It will open up the default file manager with root permission. Now you can navigate to any directory and delete anything you want.