Deleting an incorrect autocomplete/autofill entry

This is driving me absolutely bonkers. I don't know if this is properly autofill or autocomplete - the two overlap too much anyway so I'm not wasting brain cells trying to come up with a distinction that makes sense to non-engineers. ANYWAY. Here's the point.

I'm on my bank website. My login is xtnjohnson -- just like here. Only I mistyped it once, so in autofill/autocomplete (whichever it is), I get a little drop-down showing two options: xtnjohnson or xtnjohson.

I want to delete only the second option. I recall at sometime finding a very simple way that involved highlighting the offending entry and hitting either control-delete, shift-delete, command-delete, or function-delete, only I can't seem to get any of those combinations to work. And of course I can't find the thread anymore.

Is this sounding familiar to anyone? Anyone?

The solution did *not* involve dealing with the autofill preferences in *any* way -- I've seen that option and it doesn't help (a) because there's no quick way to find the website where the problem is occurring (my list is long), (b) even when I go through my list, I don't see my bank's url, (c) the place for entering my login appears to be in something like JavaScript, so I'm not sure it'd be tracked in one of those lists, and (d) I don't know that this is properly an "autofill" problem anyway.

Thank you for any advice.