If C# use as below
dt.Columns[1].Expression = "'False'"
Here dt is the input datatable …1 is the column index…(Index starts from 0) …you can as well use column name instead of column index
Expression is used to set the value to whole of the column… As you wanted false to be set we are giving False between single quotes and the value should be a string so using double quotes around it
Hope this helps
cheers