$re = '/\[\|\d+][^][()]*\([^()]*\)/';
$str = 'Do [|83] blabla83
Bo [|18] pz ([]?:)\\n la :\\n[pl]
Co [|76] pp ([]?:)
Do [|83] blabla 83 Bo [|18] blabla 18\\n la :\\n[pl] Co [|76] blabla76
Do [|83] blabla done Bo [|18] pz ([]?:)\\n la :\\n[pl] Co [|76] pp ([]?:)
';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php