@Aishwarya_Bhargava According to the requirement, If you are working on Datatables manipulation and updating the Excel Sheet, then one way would be to Concatenate the DDD+EEE Column Values first and place it in the DDD Column itself. So that You wouldn’t have to worry about the EEE Column and you can delete it with Remove Data Column Activity.
Hence, you would have 4 Column Names to be replaced with 4 new Column Names.
Next, You can just use an Assign Activity to Update the Old Column Name to New Column Name in the Below way.
DT.Columns("AAA").ColumnName = "ABC"
Where DT is the Datatable variable name.
Similarly you can update the Other Column names as well.
However there are other methods to update the Column Names, and let us know your review on this method whether this method is suitable.
If this method is not helpful please let us know more about the requirement in detail.