How do I remove linebreaks in Notepad++?

1. Highlight the lines you want to join (or use Ctrl + A to select everything)
2. Choose Edit → Line Operations → Join Lines from the menu or press Ctrl + J.

It will put in spaces automatically if necessary to prevent words from getting stuck together

CTRL+H

In Search Mode pick Extended

Find - \r\n Replace - leave it empty.

For me, using Win 7, I had to use

\r

in the Find box and type in <space> in the Replace box so that there is a single space between the last word of the current line and the first word of the next line.