$ ssh-keygen -p
Here is what the above code is Doing:
1. ssh-keygen -p is the command to change the passphrase of your SSH key.
2. -f is the option to specify the file name of your SSH key.
3. ~/.ssh/id_rsa is the path to your SSH key.
4. Enter the old passphrase.
5. Enter the new passphrase.
6. Enter the new passphrase again.