just extract the alphanumeric characters

Function RemoveSymbols(cellValue As String) As String
        valueLen = Len(cellValue)
        
        For pos = 1 To valueLen
            cellChar = UCase(Left(cellValue, 1))
            If cellChar = "A" Or cellChar = "B" Or cellChar = "C" Or cellChar = "D" Or cellChar = "E" Or cellChar = "F" Or cellChar = "G" Or _
                cellChar = "H" Or cellChar = "I" Or cellChar = "J" Or cellChar = "K" Or cellChar = "L" Or cellChar = "M" Or cellChar = "N" Or _
                cellChar = "O" Or cellChar = "P" Or cellChar = "Q" Or cellChar = "R" Or cellChar = "S" Or cellChar = "T" Or cellChar = "U" Or _
                cellChar = "V" Or cellChar = "W" Or cellChar = "X" Or cellChar = "Y" Or cellChar = "Z" Or IsNumeric(cellChar) Then
            
                newCellValue = newCellValue & cellChar
            End If
            valueLen = valueLen - 1
            cellValue = Right(cellValue, valueLen)
        Next pos
            RemoveSymbols = newCellValue
            newCellValue = ""
End Function

Sub Main()
' David Brett 9th Dec 2003
Dim Myrange    As Range
Dim Cel        As Range
    On Error Resume Next
    ' Look at formulas only, the error check prevents an error if there are no formulas in the selection
    Set Myrange = Intersect(Selection, Selection.Cells.SpecialCells(xlFormulas))
    On Error GoTo 0
    ' Leave Main sub if there are no formulas
    If Myrange Is Nothing Then Exit Sub
    With Application
        .ScreenUpdating = False
        .Calculation = xlCalculationManual
    End With
    For Each Cel In Myrange.Cells
        ' Four valid arguments
        ' "Rel" = Relative Referenced
        ' "Abs" = Absolute Referenced
        ' "Row" = Absolute Row Referenced
        ' "Col" = Absolute Column Referenced

        'This example converts every second cell reference of each formula in the selection to Absolute
        ' ReplaceRef Function = (Pattern to find formulas, Desired Reference, formula ref to be changed)
        Cel.Formula = ReplaceRef(Cel.Formula, "([$]{0,1})([A-Z]{1,2})([$]{0,1})(\d{1,5})", "Abs", 2)
    Next
    With Application
        .ScreenUpdating = True
        .Calculation = xlCalculationAutomatic
    End With
End Sub

Function ReplaceRef(str1 As String, Patrn As String, replStr As String, FormulaRef As Integer)
Dim Reg
Dim RegEx
Dim Subm
Dim NewForm    As String

    Set RegEx = CreateObject("vbscript.regexp")       ' Create regular expression.
    RegEx.Global = True
    RegEx.Pattern = Patrn                             ' Set pattern.
    RegEx.IgnoreCase = True                           ' Make case insensitive.
    Set Reg = RegEx.Execute(str1)
    If Reg.Count < FormulaRef Then                    'If the formula is not long enough then exit
        ReplaceRef = str1
        Exit Function
    End If
    'the first submatch is (0) so submatch n = Reg(n-1)
    Set Subm = Reg(FormulaRef - 1).submatches
    Select Case Application.WorksheetFunction.Proper(replStr)
        Case "Rel"
            NewForm = Subm(1) & Subm(3)
        Case "Abs"
            NewForm = "$" & Subm(1) & "$" & Subm(3)
        Case "Col"
            NewForm = "$" & Subm(1) & Subm(3)
        Case "Row"
            NewForm = Subm(1) & "$" & Subm(3)
        Case Else
            'conversion input was invalid
            ReplaceRef = str1
            Exit Function
    End Select
    ReplaceRef = Application.WorksheetFunction.Replace(str1, Reg(FormulaRef - 1).FirstIndex + 1, Len(Reg(FormulaRef - 1)), NewForm)
End Function

Sub yWriteAlphaNumericOnlyFromColumnCtoColumnE()
    For Each cell In Intersect(ActiveSheet.UsedRange, Columns("c"))
        For j = 1 To Len(cell)
            If Asc(Mid(cell, j, 1)) > 47 And Asc(Mid(cell, j, 1)) < 59 Or _
                Asc(Mid(cell, j, 1)) > 64 And Asc(Mid(cell, j, 1)) < 91 Then _
                ylet = ylet & Mid(cell, j, 1)
            cell.Offset(0, 2) = ylet
        Next
        ylet = ""
    Next
End Sub