If you want to remove a column you do not need, you can delete a column.
Now that you have used the columns for the concatenation, you can delete them and only keep the result.
- Click the column you want to delete, Email_First_Name for example.
- Click the white arrow or right-click the column to open the contextual menu.
Click Delete Column.
- Proceed the same way to delete the Email_Last_Name column and the Email_Domain column.
The selected columns are deleted.