If you do not like (like me) to be always using the command "If you please" in Linux, ie "sudo", and then you must enter a user password! That sucks, does not believe?
So, to disable the password prompt when you switch to root, you can do the following:

1 - sudo visudo
# User privilege specification
root ALL = (ALL) ALL
(Uncomment the previous line)

2 - add your user to sudo group in /etc/group

3 - From now on, whenever the command line, just do sudo su, and not you are prompted password:)

Warning: The team Aventux, advises not make this change in servers, where security must be taken into account too. Now on workstations is not so serious, anyway, it is your account and risk.

Note: This was tested on Debian. I think that also works in this based distros (Ubuntu and others). Other non-Debian distributions also must have a very similar process.

To conclude let one more tip. After making the settings described above, to set up a shortcut menu of programs so that no password is requested, putting sudo before the command. I give the example of Synaptic. It always asks to start the root password, then you must edit the configuration of the shortcut and change the field where it says "Command: synaptic" to "Command: sudo synaptic".