Edit: whoops, I misread your post a little bit.
If you want to remove an existing domain from your certificate, you might be able to modify the Le_Alt line in ~/.acme.sh/trillionpictures.com/trillionpictures.com.conf and remove radical-4.com from it.
Then when you run the below, it should hopefully perform a renewal without including radical-4.com:
acme.sh --renew -d trillionpictures.com