People have just started using Google+ and so far we are hearing lot of positive feedback. But if you do want to use Google Plus and delete your Google+ content completely then you can follow the below steps.
Click on your profile link appearing on top of Google+ page and select Account settings from the available menus.
In the Google Accounts, navigate to Services section under Account overview screen.
In the Services section, click the link provided for Delete profile and social features.
This would display the following Delete Google+ content or entire Google Profile option. Select the first radio option to Delete Google+ content and mark the checkbox asking for your confirmation then click the Remove selected services.
This will downgraded your Google+ service i.e your Google+ Circles, +1’s, posts, comments and other shared content will be deleted.