How to Erase Internet Files Permanently From a Mac

by Avery Martin ; Updated August 24, 2017

People with access to your Mac can locate clues about your financial information, social media websites, login information and other personal information. If you decide to store your passwords with your browser, people can also access financial records and download bank statements and access your private accounts. Even if you delete your browser history, a tech-savvy person may still have the ability to recover deleted files on your computer. You can remove all of your Internet files permanently by first clearing your Safari browser history and then wiping the free space on your hard drive with the Mac OS X Disk Utility.

Clear History Options

Click the "History" drop-down menu, select "Clear History..." and check the "Also Reset Top Sites" box, if desired. Click the "Clear" button to remove your history immediately. This option doesn't remove passwords and other website data that could potentially identify the websites you visited.

Click the "History" drop-down menu and select "Show Full History" to delete individual history options. Click on the "History" tab in the sidebar and then select each website you want to clear. Press the "Delete" button on your keyboard to delete the items you selected.

Click the "Safari" drop-down menu, select "Preferences" and click the "General" tab. Choose the "Remove History Items" drop-down menu and choose a time interval to automatically delete your history. Options exist to automatically delete data each day, week, every two weeks, monthly, yearly or manually.

Reset Safari

Open Safari, click the "Safari" drop-down menu and select "Reset Safari." Resetting Safari also clears your history along with all of your saved password data, download history and any other information stored in Safari. Resetting Safari essentially restores Safari to its default settings, erasing all your modifications in the process.

Check each of the available options on the Reset Safari page. The first option labeled Clear History deletes your history. The remaining options enable you to remove top site information, delete preview images, reset any location warnings and delete other information that can be used to determine the websites you visited. If you want to keep certain data, don't select the option for that data. For example, keep your passwords by not checking the "Remove Saved Names and Passwords" check box.

Click the "Reset" button to remove all of your personal files and data.

Erase Free Space

Select the "Go" drop-down menu on your Mac and click "Utilities" on your Mac menu bar. Double-click the "Disk Utility" program icon and then select your hard drive from the sidebar.

Click the "Erase" tab and select the "Erase Free Space" button. When you delete items from your hard drive, the date stays on the hard drive but becomes invisible to you. The erase free space option writes over the data several times with numbers, essentially using blank data to make it impossible to recover your information.

Set the slider to "Fastest" to perform a quick erase of all your files. Set the slider to "Most Secure" to overwrite your hard drive seven times. Or, choose the middle point on the slider to get a good compromise between a fast erase and the most secure option. The higher value you choose, the more times the free space on your hard drive gets overwritten by "blank" data.

Tip

  • If you have an SSD drive in your Mac computer, you don't need to and can't overwrite the free space on your computer. The option to erase free space appears grayed out on SSD drives.

    Information in this article applies to Mac OS X Mountain Lion. It may vary slightly or significantly with other versions or products.

Tips

  • The Fastest option on the Disk Utility slider writes over the hard disk using zeros and does only one pass.
  • The middle 3-pass secure erase option writes over your data three times. It provides more security than the Fastest option but takes three times as long to complete. The 3-pass option meets the Department of Energy standard for deleting data.
  • The Most Secure option on the Disk Utility slider writes over data seven times and uses a combination of ones and zeros. This option uses the Department of Defense 5220.22-M specification for securely deleting data.
  • You don't need to worry about losing your data when using the erase free space option.
  • If you receive a warning that you are running low on disk space while erasing the free space on your Mac, you can safely ignore the warning. This occurs as the procedure nears completion.

Warnings

  • If you have an SSD drive in your Mac computer, you don't need to and can't overwrite the free space on your computer. The option to erase free space appears grayed out on SSD drives.
  • Information in this article applies to Mac OS X Mountain Lion. It may vary slightly or significantly with other versions or products.

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About the Author

Avery Martin holds a Bachelor of Music in opera performance and a Bachelor of Arts in East Asian studies. As a professional writer, she has written for Education.com, Samsung and IBM. Martin contributed English translations for a collection of Japanese poems by Misuzu Kaneko. She has worked as an educator in Japan, and she runs a private voice studio out of her home. She writes about education, music and travel.

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