I’d say, in each iteration of the foreach loop, do a str_replace where you replace the comma with an empty string before you echo it:
$tag = str_replace(',','',$tag);
And as a side note: even though I don’t know the rest of your HTML, I doubt that h6 is the semantically correct element to use. It would probably be better to use a div instead; to make it look as you like you should style it with CSS.
