If you have submitted a pull request and had a DCO error, this is one way to fix it.

Step-by-step guide

First, change your GitHub settings

  1. Go to the "email" settings page
  2. If "Keep my email addresses private" is checked, uncheck it.
  3. Make sure your Primary email address is valid and has been verified

Second, change your GitHub Desktop for Windows settings

  1. File, options
  2. git
  3. Set your name and email address to your public address

Third, you can use your command line to update the remote

  1. Using GitHub Desktop, open a new command prompt:

2. You can then use git rebase or git commit --amend  -s ... to fix things up as needed. You'll probably need to do a git push --force-with-lease or similar.