If you mean is there a way to CRUD Tenant objects, there isn't any because there isn't any such thing as a tenant object. It's simply a string that operates as a discriminator in the database. You need to pass in your own tenant string.
If you mean creating a user there isn't much too it. You have to implement a RavenDB Repository. (see here Sample RavenDb implementation), then simply call the create method on the UserAccountService
var securitySettings = new SecuritySettings
{
AllowLoginAfterAccountCreation = true,
MultiTenant = true,
};
var config = new MembershipRebootConfiguration<HierarchicalUserAccount>(securitySettings);
var repository = new RavenUserAccountRepository("");
var uas = new UserAccountService<HierarchicalUserAccount>(config, repository);
var userAccount = uas.CreateAccount("tenant_id", "username", "password", "test@test.com");