Sub combineRows()
Dim rg As Range
Dim delimiter As String, s As String
Dim i As Long, k As Long, n As Long, nData As Long
Dim vData As Variant, vResults As Variant

delimiter = ", "
Set rg = Range("A2").CurrentRegion
Set rg = rg.Offset(1, 0).Resize(rg.Rows.Count - 1, rg.Columns.Count)
n = rg.Rows.Count
nData = Application.CountA(rg.Columns(1))
vData = rg.Value
ReDim vResults(1 To nData, 1 To 2)

For i = 1 To n
If vData(i, 1) <> "" Then
k = k + 1
vResults(k, 1) = vData(i, 1)
If s <> "" Then
If i > 1 Then vResults(k - 1, 2) = s
End If
s = IIf(vData(i, 2) = "", "", vData(i, 2))
Else
If vData(i, 2) <> "" Then
If s = "" Then
s = vData(i, 2)
Else
s = s & delimiter & vData(i, 2)
End If
End If
End If
Next
If s <> "" Then vResults(k, 2) = s

rg.ClearContents
rg.Resize(nData, 2).Value = vResults
End Sub

Set rg = Range("A2").CurrentRegion

Sub a_b_merge()
lastRow = ActiveSheet.UsedRange.Rows(ActiveSheet.UsedRange.Rows.Count).Row
delimiter = ", "

For i = 1 To lastRow
Cells(i, 3) = Cells(i, 1) & delimiter & Cells(i, 2)
Next i
Columns(1).EntireColumn.Delete
Columns(1).EntireColumn.Delete

lastRow2 = ActiveSheet.UsedRange.Rows(ActiveSheet.UsedRange.Rows.Count).Row

For j = 1 To lastRow2
If Cells(j, 1) = "" Then
Rows(j).EntireRow.Delete
lastRow2 = lastRow2 - 1
j = j - 1
End If
If j = lastRow2 Then
Exit For
End If
Next j
End Sub