How do I remove an SSH key from the Cloud Manager?
This is coming from a blind person's perspective, but perhaps it will help you.
In the cloud manager, click on the button with your username, which should then pull up a menu that presents a list of various options. One of those options is SSH keys. Once you've clicked on that, you should be able to click the delete button next to any key you wish to remove, which are presented in a table and labeled with the names you created them with.
I hope this helps.
Please follow this, it will help you out: