Dim deleteRows()
    Dim lastRow As Long

    'get the last row
    lastRow = Sheet1.Range("H1").End(xlDown).Row

    'iterate from the last row to the first row
    Dim i As Long
    For i = lastRow To 1 Step -1

        'test this row we are on for your first condition
        If (Sheet1.Range("H" & i).Value = "Stock" Or Sheet1.Range("H" & i).Value = "Custom") _
                And Sheet1.Range("G" & i).Value > Now() + 3 Then
            Sheet1.Rows(i).Delete
        'test for second condition
        ElseIf Sheet1.Range("H" & i).Value <> "STOCK" And Sheet1.Range("H" & i).Value <> "FABRIC" _
                And Sheet1.Range("G" & i).Value > Now() + 20 Then
            Sheet1.Rows(i).Delete
        End If

    'on to the next row up
    Next i
End Sub

Option Explicit

Sub DeleteMe()

Dim ws As Worksheet: Set ws = ThisWorkbook.Sheets("Sheet1")
Dim i As Long, DeleteMe As Range

For i = 2 To ws.Range("A" & ws.Rows.Count).End(xlUp).Row
    If ws.Range("H" & i) = "Stock" Or ws.Range("H" & i) = "custom" And ws.Range("G" & i) > Now() + 3 Then
        If DeleteMe Is Nothing Then
            Set DeleteMe = ws.Range("H" & i)
        Else
            Set DeleteMe = Union(DeleteMe, ws.Range("H" & i))
        End If
    ElseIf ws.Range("H" & i) <> "Stock" And ws.Range("H" & i) <> "Fabric" & ws.Range("G" & i) < Now() + 14 Then
        If DeleteMe Is Nothing Then
            Set DeleteMe = ws.Range("H" & i)
        Else
            Set DeleteMe = Union(DeleteMe, ws.Range("H" & i))
        End If
    End If
Next i

If Not DeleteMe Is Nothing Then DeleteMe.EntireRow.Delete

End Sub