Your privacy is important to the library, which is why we have measures in place to protect confidentiality. All the library's public computers are designed to clean patron data every single time a patron logs out of the computer. All browsing history is erased.
Furthermore, If anything was has been saved to the hard drive of the computer, it will be erased when you logout. In addition to the cleaning that takes place during logout, the computer is completely restored to its original state.
Unfortunately, you can't see this in action by clicking tools --> delete browser history. To ensure this security measure works, the library asks you to log out. If you're curious about it, you can then log back in to see that the security is in place. Once you log out and then you (or anyone else) logs in, you will not find any browser history.