Here’s a command that will remove an offending line from a file’s history in all your branches:
git filter-branch --tree-filter 'sed -i "/sensitive information/ d" filename' -- --all
This checks out every revision, runs the sed command on it, then commits that revision back.
The sed command in this case matches any lines containing the pattern sensitive information in the file named filename and deletes those lines.
Note: it’s good if you have a backup, and try the sed script on its own first to make sure it’s doing what you want, because it can take quite a while to run on a long history.