Hello,
By backup, if you're just looking to get a copy of the current cert/key, you'd call:
CMD_API_SSL
method: GET
domain=domain.com
without any options apart from the domain name.
DA will return the cert/key, then you can do what you wish with them.
To "remove" a certificate, it's basically just the process of changing the domain to use the server's shared certificate, instead of using a posted cert/key. It would be as simple as:
CMD_API_SSL
method: POST
domain=domain.com
action=save
type=server
John