How can I group like rows ?

Iwould not tackle this with group by.

Add a custom colum:

Table.AddColumn(Source, "To Be Removed", each Table.MatchesAnyRows(Source, (R) => R[KEY] = [KEY] and Text.Lower(R[NAME]) = "removed"))

I am not at my laptop, so =have not tested this...

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Kees Stolker

A big fan of Power Query and Excel

Here is another possible solution...

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7DEFDQ2MsRmMlg4FgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, Key = _t]),
    set_types = Table.TransformColumnTypes(Source,{{"Name", type text}, {"Key", type text}}),
    keys_to_remove = List.Transform(List.PositionOf(set_types[Name], "Removed", Occurrence.All), each set_types[Key]{_}),
    remove_keys = Table.SelectRows(set_types, each not List.Contains(keys_to_remove, [Key]))
in
    remove_keys

EaglesTony Try this:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7BUio0FAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [NAME = _t, KEY = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"NAME", type text}, {"KEY", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"KEY"}, {{"Table", each _, type table [NAME=nullable text, KEY=nullable text]}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.ToList(Table.SelectColumns([Table],"NAME"))),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "Custom.1", each List.Contains([Custom], "Removed")),
    #"Filtered Rows" = Table.SelectRows(#"Added Custom1", each ([Custom.1] = false)),
    #"Expanded Table" = Table.ExpandTableColumn(#"Filtered Rows", "Table", {"NAME"}, {"NAME"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Table",{"Custom", "Custom.1"})
in
    #"Removed Columns"

And another approach, which seems to execute quite rapidly:

Original

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7DEFDQ2MsRmMlg4FgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [NAME = _t, KEY = _t]),
    
    filter = Table.SelectRows(Source, (r)=>
        let 
            allKeys = Table.SelectRows(Source, each [KEY] = r[KEY])
        in 
            not List.Contains(allKeys[NAME],"Removed",Comparer.OrdinalIgnoreCase))
in
    filter

Result

Assuming the source:

Power Query:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7BUio0FAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, Key = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Name", type text}, {"Key", type text}}),
    #"Trimmed Text" = Table.TransformColumns(#"Changed Type",{{"Name", Text.Trim, type text}, {"Key", Text.Trim, type text}}),
    #"Filtered Rows" = Table.SelectRows(#"Trimmed Text", each ([Name] = "Removed")),
    #"Merged Queries" = Table.NestedJoin(#"Trimmed Text", {"Key"}, #"Filtered Rows", {"Key"}, "Filtered Rows", JoinKind.LeftAnti),
    #"Removed Columns" = Table.RemoveColumns(#"Merged Queries",{"Filtered Rows"})
in
    #"Removed Columns"

or

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7BUio0FAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, Key = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Name", type text}, {"Key", type text}}),
    #"Trimmed Text" = Table.TransformColumns(#"Changed Type",{{"Name", Text.Trim, type text}, {"Key", Text.Trim, type text}}),
    #"Added Custom" = Table.AddColumn(#"Trimmed Text", "To Be Removed", each Table.MatchesAnyRows(Source, (R) => R[Key] = [Key] and Text.Lower(R[Name]) = "removed")),
    #"Filtered Rows" = Table.SelectRows(#"Added Custom", each ([To Be Removed] = false)),
    #"Removed Columns" = Table.RemoveColumns(#"Filtered Rows",{"To Be Removed"})
in
    #"Removed Columns"

Output:

Hi EaglesTony, you have many solutions here...
Another one:

Output:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckxJSU1R0lFycQxx1DU0MlaK1YlWCkrNzS/DFHbOz83NLClBSJiYmoElUAwxt7BUio0FAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [NAME = _t, KEY = _t]),
    FilteredName = Table.RemoveColumns(Table.Join(Source, "KEY", Table.RenameColumns(Table.SelectRows(Source, each [NAME] = "Removed")[[KEY]], {{"KEY", "KEY2"}}), "KEY2", JoinKind.LeftAnti), {"KEY2"})
in
    FilteredName