It is not possible to disable private browsing. Can you please let us know why you are trying to disable it, and we can possibly give you a better solution.

If you are worried about people using it to visit websites they shouldn't, than you should use a network based content monitor (if they are legal in your jurisdiction) to block access to websites.

You used to be able to do this in the regular Firefox with third-party addons, but they are no longer compatible with the webextensions that Firefox uses now.

Disabling private browsing is really only intended for enterprise environments, as it requires group policy on your computer. However, it's fairly simple to implement this feature. You need to be the system administrator and have a version of Windows that supports group policy.

You just need to do the following:

1. Download the ZIP file template from here
2. Copy and paste the contents of the windows folder of that ZIP file to C:\Windows\PolicyDefinitions
3. Press the Windows key + R
4. Enter gpedit.msc
5. Under look under Computer Configuration > Administrative Templates > Mozilla > Firefox
6. Find the Disable Private Browsing
7. Set that to enabled
8. Restart your computer

WARNING: If you are not computer savvy, I would not recommend playing with group policy on your system, since it can have negative impacts if not done correctly.

You can use a policies.json file, see:

• https://github.com/mozilla/policy-templates/

DisablePrivateBrowsing

This policy removes access to private browsing

{
  "policies": {
    "DisablePrivateBrowsing": true
  }
}

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-policiesjson
• https://support.mozilla.org/en-US/kb/customizing-firefox-using-group-policy
• https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig

The reason for wanting to disable the private browsing should be obvious - you may have kids in your house using your computer and chances are you don't want them to have the option of going places they shouldn't without their parents knowing about it.

danielsjoo said

The reason for wanting to disable the private browsing should be obvious - you may have kids in your house using your computer and chances are you don't want them to have the option of going places they shouldn't without their parents knowing about it.

Would you please take a look at this article :

https://support.mozilla.org/en-US/kb/block-and-unblock-websites-parental-controls-firef

(this may not apply to the OP of this thread though .... )