I have to remove string like 23x45 in vb6 how to do it

Regex regex = new Regex(@"^(?<leftpart>[\d]?)/(?<rightpart>[\d]?)$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
Match m = regex.Match(yourString);
 
if (m.Success)
{
   string left = m.Groups["LeftPart"].Value;
   string right = m.Groups["RightPart"].Value;
 
   while (left.Length < 4)
      left.Insert(0, "0");
 
   while (right.Length < 2)
      right.Insert(0, "0");
}
else
{
   // Handle error
}