HELP PLEASE with Macro: delete row if value in row D is below "x" or above "y"

The most efficient way I know to delete rows using VBA is to use auto-filter feature

You can place this code into a module and try to change the sheet names range and variables x , y to the one you have. 

I wrote this code for the example I have attached. 

you can see that it runs the code on Sheet1 and the range is set after the 25th row, it will ignore the previous rows up to 25th row. ws.Range("A25:O" & lastRow)  also you can change your column from O to whatever your column is

you can assign values to x and y in the code.

if you download the workbook and you run the code in it. you will see what it will do to the data.

Please remember when running any macro, run it on a copy of workbook meaning (you must have a backup copy) because you cannot undo a macro action,  just in case if you click on save by accident.

Sub Test()

Dim x As Double, y As Double
      x = 7
      y = 4
    Dim ws As Worksheet
    Dim rng As Range
    Dim lastRow As Long

    Set ws = ActiveWorkbook.Sheets("Sheet1")

    lastRow = ws.Range("A" & ws.Rows.Count).End(xlUp).Row

    Set rng = ws.Range("A25:O" & lastRow)
    With rng
    .AutoFilter Field:=4, Criteria1:="<" & x, Operator:=xlAnd, Criteria2:=">" & y
      .Offset(1).Resize(.Rows.Count - 1).SpecialCells(xlCellTypeVisible).EntireRow.Delete
    End With

    ws.AutoFilterMode = False
End Sub