Well the problem might lay with what you have done, or it might lay with what you havent yet done, or it might lay with that you didnt really tell us exactly what you wanted done.

(1) where did you put the code you were given, its ment to go into a remote script file press alt-r in mirc then select file/new

(2) the <nick> is ment to be changed to the nick in question , did you do that?

(3) I made an asumption it was a nick saying soemthing in channel that you wanted to effect. is it?
(b) you asked for stripping to be turned OFF, but then proceedded to ask for stripping to be turned ON for one specific nick, which was it?
(c) what is the nature of the reason you need the color stripped/bold/etc stripped from this nicks text anyway?

on ^*:text:*:*:{ if ($nick == nick) { haltdef | echo -itlbfmrc normal $iif($chan,$chan,$nick) $+((<,$nick,>) $strip($1-) } }
on ^*:action:*:*:{ if ($nick == nick) { haltdef | echo -itlbfmrc action $iif($chan,$chan,$nick) * $nick $strip($1-) } }

* i think they well work for channel or pms