This post is older than a year. Consider some information might not be accurate anymore.
vi or vim (vi improved) has powerful ways to delete line. This post gives some examples.
The command for delete is
:d. Delete current line
Delete line 10
Delete from start to line 30
Delete from line 50 to end ($)
Delete blank line (:g will execute a command on lines which match a regex. The regex is ‘blank line’)