delete entries form about:config

How to

[Shakushinnen]

Dear....
Recently I read an article on this forum titled, "Making Firefox as fast as Opera. Thank you to MatthewHSE for posting it. However, when I was changeing the Firefox settings I mistakenly added a wrong entry and have not been able to remove it. Could someone please tell me how to do it.
Thanks,
John

[drbrain]

1: Don't worry about it.
2: Right-click it and select 'reset' (If such a pref is ever added, it'll have the "right" value.)
3: If you still want to get rid of it, shutdown the browser, go to the profile directory (homedir/Application Data/Mozilla/Firefox/default.XXX/
4: Edit prefs.js and remove the offending preference.

[Shakushinnen]

Thanks drbrain
John