I have tried to follow the following:
How to delete selected text in VI editor
but
5dd
gives
E492: Not an editor command: 5dd
I then tried:
5d
Which only deletes a single line. How can I delete multiple lines?
I find this easier
https://superuser.com/questions/170795/how-can-i-select-and-delete-lines-of-text-in-vi