There's a couple of ways, one way is
- Get search results
SPC /and type in your search string
SPC x Sand search string - where x is your scope indicator (p for project, d for directory, etc..)
- Once you have the occurences you want, hit
C-c C-einside the helm buffer to put all your match occurences and puts them into a special buffer called the edit buffer or something like that
- in that buffer you can use any commands you'd normally use on a buffer
C-c C-cto commit your changes.