How to clear internet history permanently?

my home PC contains certain #@$$#@ sites and I want to clear them . please tell me HOW ?How to clear internet history permanently?
To delete Internet Explorer search history


**************************************鈥?br>

1. Open a new Internet Explorer window.


2. Click the Tools menu.


3. Select Internet Options.


4. On the General tab, click the Clear History button.


5. On the Content tab, click the Auto Complete button.


6. Click the Clear Forms button.


7. Click the OK button.





Firefox search history


**********************


1. Open a new Firefox window.


2. Click the Tools menu.


3. Choose Clear Private Data.


4. Make sure the 'Browsing History' and 'Saved Form and Search History' check boxes are selected.


5. Click the Clear Private Data Now button.


How to clear internet history permanently?
Go to Tools then press delete browsing history that's it...
Try disk cleanup