How can I stop Firefox from autocompleting the wrong site in the location bar? [duplicate]

There are a few sites I have visited by mistake. These are not bookmarked, but despite repeated clearing of browser history, both from within Firefox, and using CCleaner, Firefox keeps suggesting these sites via autocomplete in the location bar. This happens on both OSX and Windows.

For example, one time, about 23 versions ago, I typed vim and then accidentally pressed ⌘-Enter instead of ⌘-Shift-Enter. The latter would have browsed to www.vim.org whereas I ended up on www.vim.com.

To this day, when I type vim in the location bar, I am offered vim.com, and not vim.org as the first choice even though I have cleared history many times, and vim.org is bookmarked:

How can I get Firefox to offer vim.org (which is bookmarked) instead of vim.com (which is not bookmarked) when I type vim in the location bar?

PS: Search suggestions in both the search bar and the location bar are disabled.

PPS: On my MacBook Pro, if I press Delete, or ⌘-Delete, or Shift-Delete, it clears vim.com from the location bar, but the same thing happens again the next time I type vim into the location bar.

PPPS: The magic of asking on SuperUser strikes. Doing the same thing I have done before, delete from auto-complete, clear history, and then clean using CCleaner, I now have what I want.

As you're typing the v i ... in the location bar and the autocomplete menu pops up underneath, use the arrow keys to select/highlight the unwanted entry, then press the DEL key to remove it from the list.

It should simply be a case of hovering your mouse over the item you want removed and hitting the DEL key (Note on Mac, you may need to use SHIFT + DEL or with an extended keyboard SHIFT + BACKSPACE.)

More information here.