If you need to remove line breaks from text in MS Word you can do the next simple actions:

Ctrl+A to select all text.
Ctrl+H to open the Find & Replace dialog box. In "Find what", type "^p^p". The "^p" means a line break. In "Replace with", type "===". (This is to make sure that only single line breaks will be replaced.)
Click on "Replace All".
Do another search and replace. For "Find what", use "^p". For the replacement, use " " (space).
Finally, we will replace the replacement above for two consecutive hard line breaks. Search for "===" and replace it with "^p".