Anaconda on Ubuntu - Error in permission to update using conda command

On my laptop on windows 8.1 I have vmware and ubuntu 16.4 installed.

I recently installed Anaconda 2.7 (x64) on it. The directory where anaconda is installed, is:

 /home/anaconda2/

When I tried to use the following command to update packages, I got errors as mentioned below:

 conda update --all

Error

 Error: Missing write permissions in: /home/anaconda2

I tried to use sudo and also tried by writing following permission under visudo

madhu ALL=(ALL:ALL)  ALL

Nothing worked....

Can someone please help me?