From Fedora Project Wiki
Replacing Your Fedora Account System SSH Key
If for any reason you need to replace your SSH key in the Fedora Account System, use this procedure:
1. Generate a new ssh key. If you select the defaults, this command generates a ~/.ssh/id_rsa private key file, and a ~/.ssh/id_rsa.pub public key file:
ssh-keygen
1. Go to https://admin.fedoraproject.org/accounts/
1. Select 'Login' in the menu on the left
1. Login with your username and password
1. Select 'My Account' on the menu at the top
1. Select 'Edit' on the 'Your Fedora Account' page
1. Upload the ~/.ssh/id_rsa.pub public key file that you generated in the first step.
1. Select 'Save'.
That's it, you're done. Remember that the ~/ssh/id_rsa private key file should be safeguarded.