Find row with latest date and keep one

PowerBeeEye 

Continuing on the code you had above:

    Row_Group_by_ForestDNSName = Table.Group(Row_Filter, {"ForestDNSName"}, {{"Count", each _, type table}}),
    Extract_Latest_Data = (TT as table) =>
  Table.SelectRows(TT, each [Scan Date] = List.Max(TT[Scan Date])),
    Custom_Column_LatestData = Table.AddColumn(Row_Group_by_ForestDNSName, "LatestData", each Extract_Latest_Data([Count])),
    Column_Remove_Except_LatestData = Table.RemoveColumns(Custom_Column_LatestData,{"ForestDNSName", "Count"}),

    #"Added Custom" = Table.AddColumn(Column_Remove_Except_LatestData, "Custom", each Table.FirstN([LatestData],1)),
    #"Expanded Custom" = Table.ExpandTableColumn(#"Added Custom", "Custom", {"Scan Date", "ForestDNSName"}, {"Scan Date", "ForestDNSName"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Custom",{"LatestData"})

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