If I hit Ctrl+n in Vim, I'll get a list of suggested autocomplete options in a popup box.

This is fine... but if I decide I don't want to autocomplete after all, I'm not quite sure what to press to revert the suggestion.

For example, suppose I type rea, hit Ctrl+n, and autocomplete pops up with really_long_method_name_damn_this_is_annoying, and I don't want that. I can't quite figure out how to revert the syntax back to just rea... I have to manually delete the unwanted characters.

I'm guessing this is a pretty straightforward thing, but still, if anyone knows how, please let me know.