You need to update the environment variable to fix the error. To update the environment variable, follow these steps:
1. Go to the 'Control panel', Click on 'System and Security' and then on 'System'.
2. On the left panel, you will find 'Advanced system settings'. Click on that and it will open a popup window.
3. On the popup window, click on 'Environment variables'. You will see a new popup window.
4.On the new popup window, select 'Path' under 'User variables'. Double click on that and it will open another popup window. In that popup window, click on 'new' to add the installation folder of Anaconda.
e.g. if your installation folder is C:\Users\xyz123\Anaconda3\, add these two folders to environment variable.
Here xyz123 is username.