Hi @Sean Liming ,
- Azure Sphere does not appear in portal as it is not an Azure Resource accessible via Azure Resource Manager, this will hopefully change in the near future, please keep an eye out for more details.
- A kit is claimed to a tenant, once this has been performed, there is no mechanism available today to unclaim a kit and detach it from the tenant.
The reason you're unable to find your tenant is because it was migrated from the pre-release service and isn't visible through the normal mechanisms. As noted, we are looking into this matter for you and I'll update once I have more information.
Many thanks