get HKLM.software.....{userSID}

GetComputerSID.pas

uses
  SysUtils,
  Variants,
  ActiveX,
  ComObj;

function ConvertSidToStringSid(Sid: PSID; out StringSid: PChar): BOOL; stdcall;  external 'ADVAPI32.DLL' name {$IFDEF UNICODE} 'ConvertSidToStringSidW'{$ELSE} 'ConvertSidToStringSidA'{$ENDIF};

function SIDToString(ASID: PSID): string;
var
  StringSid : PChar;
begin
  ConvertSidToStringSid(ASID, StringSid);
  Result := string(StringSid);
end;

function GetLocalComputerName: string;
var
  nSize: DWORD;
begin
  nSize := MAX_COMPUTERNAME_LENGTH + 1;
  SetLength(Result, nSize);
  if not GetComputerName(PChar(Result), nSize) then
    Result := '';
end;

function GetComputerSID:string;
var
  Sid: PSID;
  cbSid: DWORD;
  cbReferencedDomainName : DWORD;
  ReferencedDomainName: string;
  peUse: SID_NAME_USE;
  Success: BOOL;
  lpSystemName : string;
  lpAccountName: string;
begin
  Sid:=nil;
  try
    lpSystemName:='';
    lpAccountName:=GetLocalComputerName;

    cbSid := 0;
    cbReferencedDomainName := 0;
    // First call to LookupAccountName to get the buffer sizes.
    Success := LookupAccountName(PChar(lpSystemName), PChar(lpAccountName), nil, cbSid, nil, cbReferencedDomainName, peUse);
    if (not Success) and (GetLastError = ERROR_INSUFFICIENT_BUFFER) then
    begin
      SetLength(ReferencedDomainName, cbReferencedDomainName);
      Sid := AllocMem(cbSid);
      // Second call to LookupAccountName to get the SID.
      Success := LookupAccountName(PChar(lpSystemName), PChar(lpAccountName), Sid, cbSid, PChar(ReferencedDomainName), cbReferencedDomainName, peUse);
      if not Success then
      begin
        FreeMem(Sid);
        Sid := nil;
        RaiseLastOSError;
      end
      else
        Result := SIDToString(Sid);//+' '+SIDToString(^cbSid);
    end
    else
      RaiseLastOSError;
  finally
    if Assigned(Sid) then
     FreeMem(Sid);
  end;
end;

procedure Main();
begin
    Console.WriteLine(GetComputerSID);
end;