$text =~ s/<SCRIPT[^>]>     # the opening <SCRIPT...> tag
           .*?              # as few chars as possible until...
           (?:</SCRIPT>|$)  # closing script tag or the end of the text ($)
          //xgis;           # (x) comments (g)lobal, case (i)nsensitive,
                            # treat string as (s)ingle line

# uncommented version
$text =~ s/<SCRIPT[^>]>.*?(?:</SCRIPT>|$)//gis;