Power Query - remove columns based on condition

See the working here - Open a blank query - Home - Advanced Editor - Remove everything from there and paste the below code to test

Below I have used 1-0.95 which means if count is less than 95% then remove it. You can adjust it accordingly 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("XYs3DsAwDAP/otlLetb03rMZ/v83YkcQYHoQwONRWlNFiiJ7iT0ySlPtgqJUuGHO/s4VLRfiO865cI96QBwRJ86F8MxcCi84XwO92RB7fsf5gXgG3xfqG/EJ1q+nzQc=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t, Column4 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", Int64.Type}, {"Column3", Int64.Type}, {"Column4", Int64.Type}}),
    RowCount = Table.RowCount(#"Changed Type"),
    ColumnsListforRemoval = List.Select(Table.ColumnNames(#"Changed Type"),(x)=>(List.NonNullCount(Table.Column(#"Changed Type",x))/RowCount)<(1-0.9)),
    RemoveColumns = Table.RemoveColumns(#"Changed Type",ColumnsListforRemoval)
in
    RemoveColumns

 if you want to make it on the basis of number of non blank cells say remove if a column has less than 10 non blank, then change this with line

ColumnsListforRemoval = List.Select(Table.ColumnNames(#"Changed Type"),(x)=>List.NonNullCount(Table.Column(#"Changed Type",x))<10)