Sub whatever ()

   Dim myCell as range
   Dim PmNum as string
   Dim erow

   erow = sheet1.cells(rows.count,2).end(xlup).offset(0,0).rows
   pmNum = matupdate.txtPM.value

   For each cell in worksheets("Sheet1").Range("B2:B" & erow)
         If cell.value = pmNum Then
         cell.offset(0,1).value = matupdate.txtdel.value
         ""
         ""
         End if
    Next
 End sub

erow = sheet1.cells(rows.count,2).end(xlup).offset(0,0).rows

erow = sheet1.cells(rows.count,2).end(xlup).offset(0,0).Row