Remove duplicates by prioritizing rows based on another column

Okay, please try this.  I have included comments that explain each step.

BEFORE: 

The goal is to remove rows 1, 3, 6, 8 and to have all columns present in the result.

RESULT:

SCRIPT:

There are two different options in the grouped step along with scenarios for when one would apply as opposed to the other, based on the specifics of the source data.  Currently, option 2 is in use.  To switch to option 1, add two forward slashes in front of Table.LastN and remove the two slashes at the beginning of let varTable and Table.FirstN.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("jcy5DcAgEETRXjZGaHbBVwi+irDovw0vJiFAmOQjxGOeh0IIZIgB6BHiroW3YCsQ1kt+pGT+ISNXKiu9UTcEGaL1n40x5n/F7sfZGJ0q6HtwHoIMp10qOxV7XndjdB2CDK/dKKUX", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Latest = _t, #"NVE-Nr." = _t, Item = _t, Date = _t, #"LHM-Nr." = _t, Index = _t]),
    grouped = Table.Group(
        Source, 
        // Column(s) containing the values from which you'd like duplicates removed.  
        {"NVE-Nr."},
        {
            { "Table", // Name of the new column.
                each 
                //---------------------------------------------------------
                // Option 1: Sort descending, then select the first result.
                //---------------------------------------------------------
                // This will work if there is a maximum of only two rows per NVE-Nr.
                //let varTable = Table.Sort ( _, {{"LHM-Nr.", Order.Descending}}) in
                //Table.FirstN ( varTable, 1 ),
                //---------------------------------------------------------
                // Option 2: Select the last LHM-Hr for each NVE-Nr.
                //---------------------------------------------------------
                // This will work if the row to keep always appears last in the group.
                Table.LastN ( _, 1 ),                
                type table
            }
        }
    ),
    expand = Table.ExpandTableColumn ( 
        grouped, 
        "Table",                                  // Expand the tables in this column
        List.Difference (                         // New column names
            Table.ColumnNames (                   // are the column names 
                Table.Combine ( grouped[Table] )  // in the nested tables 
            ), 
            Table.ColumnNames ( grouped )         // that do not appear in the grouped table.
        ) 
    )

in
    expand