local $/;
$_ = <DATA>;
1 while s#\[\s*(\w+)\s*(=[^\]]+)*\s*\]\s*\[\s*/\s*\1\s*\]##ig;
print;

__DATA__
[b]bold text[/b]
[color=Red]Red text text[/color]
[color=Red][b]Red bold text[/b][/color]

I need to remove the ones below: 
[b][/b]
[color=Red][/color]
[color=Red][b][/b][/Color]
[color=Red][/col] Now this is still here ysth (if that is what is wanted)
[ b ]   [ / b ] This will go now
[ foo  = bar ]   [ / foo ] ... and this too