How to toggle sidebar of a standard Salesforce page?

Hi Pranav ,

Go To Setup > Administration Setup > Manage User > Profiles > "Customer Portal Profile" > Uncheck "Show Custom Sidebar On All Pages" under "General User Permissions" section > Save

After this what you can do is create a home page component which will not have any component like search, recent items etc and assign it to Customer portal Profile.

Setup > App Setup > Home > Home Page Layout

Also ,
Setup --> Customize --> User Interface. and then you get the screen in which you can uncheck the option "Show Custom Sidebar Components on All Pages" in the Side Bar section and then check that its working in the customer portal or not.

Thanks