One way:

Option Explicit
Sub testme()
   Dim iRow As Long
   Dim FirstRow As Long
   Dim LastRow As Long
   Dim wks As Worksheet
   Dim DelRng As Range
   
   Set wks = ActiveSheet
   With wks
       FirstRow = 2
       LastRow = .Cells(.Rows.Count, "L").End(xlUp).Row
               
       For iRow = FirstRow To LastRow
           If Application.IsNumber(.Cells(iRow, "L").Value) _
            And Application.IsNumber(.Cells(iRow, "M").Value) _
            And Application.IsNumber(.Cells(iRow, "N").Value) Then
               If Application.Max(.Cells(iRow, "L").Resize(1, 3)) = 0 _
                And Application.Min(.Cells(iRow, "L").Resize(1, 3)) = 0 Then
                   If DelRng Is Nothing Then
                       Set DelRng = .Cells(iRow, "L")
                   Else
                       Set DelRng = Union(.Cells(iRow, "L"), DelRng)
                   End If
               End If
           End If
       Next iRow
   End With
       
   If DelRng Is Nothing Then
       'do nothing
   Else
       DelRng.EntireRow.Delete
   End If
End Sub

It just checks to see if each of those cells is a number (application.isnumber
is more stringent than VBA's isnumeric).  Then if they are all numbers, it
checks to see if the max = min = 0.  If yes, then delete that row.

It starts at row 2 and finishes with the last used cell in column L (could be
slightly different than what you asked).