How to remove (Underlined/ Strikethrough of characters) in Excel cells

I am researching how to remove underscore characters and keep only characters that do not have underscores in each Excel cell. For example, if the cell value is multi-line and each line has an underscore, it should be removed. Thank you to the esteemed community.

This version will split the cell content by lines iterating between each other and check if one line character is underlined. According to that, the line will be removed (everything happening in two arrays). The result will be returned two columns to the right of original one. If you like the way you should only replace targetCell.Offset(, 2).value with targetCell.value:

Sub demo_()
    Dim target As Range
    
    For Each target In Range("A2:B10").cells
        removeUnderlined target
    Next
    
End Sub

Sub removeUnderlined(targetCell As Range)
  Dim arr, nrCh As Long, arr1, i As Long, outTxt As String
  arr = Split(targetCell.value, vbLf) 'creating an array of cell lines
  
  If UBound(arr) = 0 Then 'if only a single line:
    If targetCell.Characters(1, 1).Font.Underline = xlUnderlineStyleSingle Then
        outTxt = ""      'the line will be removed
    Else
        outTxt = arr(0) 'the line text will be kept
    End If
    targetCell.Offset(, 2).value = outTxt: Exit Sub 'return the line
  Else
    For i = 0 To UBound(arr)
        nrCh = nrCh + Len(arr(i))
        If targetCell.Characters(nrCh - 1, 1).Font.Underline = xlUnderlineStyleSingle Then
            If Not IsArray(arr1) Then
                arr1 = filter(arr, arr(i), False)   'create a new array without the underlined element
            Else
                arr1 = filter(arr1, arr(i), False) 'remove the underlined element
            End If
        End If
    Next i
  End If
  If IsArray(arr1) Then
    outTxt = Join(arr1, vbLf) 'return the joined array
  Else
    outTxt = Join(arr, vbLf)  'return the joined array
  End If
  
  targetCell.Offset(, 2).value = outTxt 'return outTxt
  End Sub

If the range to be processed is huge, I can supply a much faster version. I mean, it will work only in memory, placing the return in a third array and only dropping its content at once, at the end of the code.

Edited:

The next version is very fast, processing only in memory and only dropping the final array content at once, of the code end:

Sub demo__()
    Dim rng As Range, target As Range, colNo As Long, rowNo As Long, arrFin
    
    Set rng = Range("B1:C6") 'use here the real range you need processing
    arrFin = rng.Offset(, 2).value 'placing the range in an array (just for testing...)
      'if you want to overwrite existing you should use arrFin = rng.Value
    For Each target In rng.cells
        colNo = target.column - rng.column + 1 'calculating the target column of rng
        rowNo = target.row - rng.row + 1       'calculating the target row of rng
        arrFin(rowNo, colNo) = removeUnderlined_(target) 'load the appropreate array element!
    Next
    'drop the final array content at once:
    rng.Offset(, 2).value = arrFin
End Sub

Function removeUnderlined_(targetCell As Range) As String
  Dim arr, nrCh As Long, arr1, i As Long, outTxt As String
  arr = Split(targetCell.value, vbLf) 'creating an array of cell lines
  
  If UBound(arr) = 0 Then 'if only a single line:
    If targetCell.Characters(1, 1).Font.Underline = xlUnderlineStyleSingle Then
        outTxt = ""      'the line will be removed
    Else
        outTxt = arr(0) 'the line text will be kept
    End If
    removeUnderlined_ = outTxt: Exit Function 'return only a line or null string
  Else
    For i = 0 To UBound(arr)
        nrCh = nrCh + Len(arr(i))
        If targetCell.Characters(nrCh - 1, 1).Font.Underline = xlUnderlineStyleSingle Then
            If Not IsArray(arr1) Then
                arr1 = filter(arr, arr(i), False)  'remove the underlined element
            Else
                arr1 = filter(arr1, arr(i), False) 'remove the underlined element
            End If
        End If
    Next i
  End If
  If IsArray(arr1) Then
    outTxt = Join(arr1, vbLf) 'return the joined arr1
  Else
    outTxt = Join(arr, vbLf) 'return the joined arr
  End If
  
  removeUnderlined_ = outTxt 'returning the processed cell output
End Function

I practically transformed the used processing Sub in a Function able to return the necessary string and only determined the final array row and column to fill the array elements appropriately.

If something not clear enough, please do not hesitate to (specifically) ask for clarifications. Even if I think that my comments should be enough for a good understanding of the code...