The CLI interface uses both “remove” and “delete”, and in most cases these terms can be used interchangibly. Thus, I suggest to pick one of the two, and use that consistently. Examples:

rad canonical-ref remove
rad config remove
rad remote rm

rad issue delete
rad patch delete
rad patch review --delete
rad patch label  --delete

rad unseed

(rm could be a short form of remove but should not be the full subcommand, and unseed should probably be rad seed --delete or similar.)