Certainly there it will not be harmful if you do not erase internet history saved on your computer. They are only prone to be threatening to your privacy if you are sharing your computer with other people. If you do not wish others to track the histories of your internet browsing then you should really delete these data off your computer's memory, which has also been eating up plenty of space. Basically it should be a wise thing to do. To perform this, you can follow the different steps mean for different internet browsers.
If you are using the Internet explorer, you can delete internet history by first choosing "Internet Options" from the tools menu and select the "General" tab on the "Internet Options" window. To delete the cached files, choose the "Delete" button in the browsing section. Then a small window will appear with sections such as Passwords, History, Form Data, Temporary Internet Files and Cookies. If you intend to erase only part of the files then select the corresponding data but if you wish to get rid of all the internet history you can click on the "Delete All" or "Clear History" button.
For those using Mozilla Firefox, you can begin by clicking on "Tools" on the drop down box then selecting "Clear Private Data". The window that appears upon clicking composer of diverse sections such as Cookies, Saved Form, Saved Passwords, Search History and Browsing History. You can click on the corresponding boxes to delete whatever you desire. You can select the "Clear Private Data Now" to erase internet history completely.
If your internet browser is the America Online (AOL), you should first locate the "Settings" button located on the window's top section. The click on it and select "Preferences" before opting for the "toolbar and sounds" tab. Next, click on the "clear history trail now" button to erase all your history. Apart from the above mentioned steps, you should also erase any third party applications installed on your computer to avoid information such as your store text, images, sensitive statistics and passwords in your hard drive to be vulnerable for outsiders' view. To delete internet history via such methods you will need some software as it is extremely difficult to locate these data and delete them yourself.