How can I remove lines that begin with spaces in Notepad++?

• Ctrl+H
• Find what: ^\h+.*$\R?
• Replace with: LEAVE EMPTY
• CHECK Wrap around
• CHECK Regular expression
• UNCHECK . matches newline
• Replace all

Explanation:

^           # beginning of line
  \h+       # 1 or more horizontal spaces
  .*        # 0 or more any character but newline
$           # end of line
  \R?       # optional linebreak

Screenshot (before):

Screenshot (after):

It's possible with a pure regex solution (see @Toto's answer) but perhaps the following solution, using bookmarks, is easier to grasp:

1. Open the Find dialog

2. Go to the Mark tab, search for ^ (that's 2 characters: a caret indicating 'the beginning of the line' and a space) and enable the 'Bookmark line' option. I assume your Search Mode is already set to Regular expression. Hit the 'Mark All' button.

   

3. Delete all bookmarked lines (Search → Bookmarks → Remove bookmarked lines)

You can do this:

• Hit Ctrl+H for find and replace.

• Check mark regular expression.

• Use the Regex ^\s+.* in the Find box.

• Keep Replace box blank.

• Click Replace All.