I want to learn more about the registry, and where programs usually store stuff. Let's say I've installed Chrome and want to 100% get rid of Firefox, Like Firefox never was installed.

What I've done so far is that I have used the uninstaller and then manually cleaned the install directory. I've also made sure there are no icons/folders left in the start menu. But then there is the registry.

There is a Mozilla\Firefox folder located several places, is it safe to just delete them? If I wanted to purge the system I would want to delete them?

I've got a Mozilla folder in these places (after uninstalling): - CURRENT_USER\Software - LOCAL_MACHINE\SOFTWARE - USERS***\Software

Can i delete Mozilla / Firefox folders/keys for these locations? Other places i need to delete data ( when uninstalling whatever software)?


The two places you mentioned are usually the two places that software will store keys:

data for the local machine (any user) HKEY_LOCAL_MACHINE\Software

and for your specific profile hive HKEY_CURRENT_USER\Software

A general rule of thumb for deleting registry keys is to back them up first, that way it is very easy to backout in case you had some undesirable effects. Note that deleting keys from the registry can cause your system to not boot at all, so be very careful with what you do regardless.

Select the key your about to delete (for example, Mozilla or Firefox) in regedit and then go File > Export. Pick "Selected branch" and then save it to a file. Do this for every key before you delete it!

Some cases you may need to restart to see registry changes.


You can, but if you are not very careful of what you delete, it could cause issues.

Normally Keys with the Exact same name as the program are safe to delete, not 100% accurate though, just 99.8% :-)

I started using Revo Uninstaller to do this for me.


  • Since any software could write to any registry location, application like Revo Uninstaller which track the files and registry installed during installation is a must have if you try to keep everything clean. Notice that sometimes, due to legitimate (such as tracking trial period) or illegitimate reason, applications deliberately write to obscure folder and registry location. – Martheen Cahya Paulo Jan 18 '11 at 21:22

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