Change Browser security settings

In the Browser, tap More actions > Settings > Privacy and Security.

Security settings

Remove History Items
Specify how often your device automatically deletes information from your BlackBerry Browser history.
Private Browsing
Keep your browsing information (your history, cached files, cookies, and so on) only while a browsing session is open. When you close the Browser, the information is automatically deleted. As well, any settings that you change while in private browsing mode apply only during the session, and Adobe Flash support is automatically turned off. If your administrator has turned on BlackBerry Balance technology, and you're using your work space, you can't turn on private browsing.
Accept Cookies
Cookies are used by some sites to send and receive information between the website and the Browser. Cookies can be helpful as they allow websites to remember information about your preferences and user information, but cookies can pose a security risk as well.
Clear Cookies and Other Data
Clear some or all of your saved Browser data.
Clear History
Clear your Browser history.