Maybe something like this
Option Explicit
Sub Macro1()
Const colCompany As Long = 9
Const colDateTime As Long = 2
Dim dataSheet As Worksheet
Dim dataAll As Range, dataNoHeaders As Range
Dim rowCheck As Long
Set dataSheet = Worksheets("Update Master Sheet")
Set dataAll = dataSheet.Range("C1").CurrentRegion
Set dataNoHeaders = dataAll.Cells(2, 1).Resize(dataAll.Rows.Count - 1, dataAll.Columns.Count)
Application.ScreenUpdating = False
With dataSheet.Sort
.SortFields.Clear
.SortFields.Add Key:=dataNoHeaders.Columns(colCompany), SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
.SortFields.Add Key:=dataNoHeaders.Columns(colDateTime), SortOn:=xlSortOnValues, Order:=xlDescending, DataOption:=xlSortNormal
.SetRange dataAll
.Header = xlYes
.MatchCase = False
.Orientation = xlTopToBottom
.SortMethod = xlPinYin
.Apply
End With
With dataAll
For rowCheck = .Rows.Count To 3 Step -1
If .Cells(rowCheck, colCompany).Value = .Cells(rowCheck - 1, colCompany).Value Then
If .Cells(rowCheck, colDateTime).Value <= .Cells(rowCheck - 1, colDateTime).Value Then
.Cells(rowCheck, colCompany).Font.Strikethrough = True ' for testing - remove and uncoment line below
' .Rows(rowCheck).Delete
End If
End If
Next rowCheck
End With
Application.ScreenUpdating = True
End Sub