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 menu icon 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.