#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(?:(\()|({)|\[)(?(1)[^)\d]*\)|(?(2)[^}\d]*}|[^]\d]*]))\s*"
Local $sString = "# (1437)" & @CRLF & _
"# {19} (917) (1437)" & @CRLF & _
"# {19} (1437) [1449] [2474] [2098] [1351] [508] [969]( MONDAY) [sunday]"
Local $sSubst = ""
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
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 AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm