When I do an interactive rebase, e.g.
git rebase -i HEAD~3
the rebase interactive editor (vim in my case) opens to let me edit the commits
If you're using Notepad++ on Windows for instance:
CtrlA to select everything, then Del or Backspace to delete and CtrlS save. Git will abort the rebase if the file is empty.
You may also hit CtrlC in the command prompt where git is running to stop the current rebase command. Then run git rebase --abort
to revert it.