In my case word length is "2" and I am using this regex:
text = text.replace(/\b[a-zA-ZΆ-ώἀ-ῼ]{2}\b/g, '') );
but cannot make it work with greek characters. For your convenience here is a demo:
text = 'English: the on in to of \n Greek: πως θα το πω';
text = text.replace(/\b[0-9a-zA-ZΆ-ώἀ-ῼ]{2}\b/g, '');
console.log(text);
As far as the greek characters are concerned, I try to use a range with 2 sets: "Greek and Coptic" and "Greek Extended" (as seen on unicode-table.com).