@Dirk H Rober Thanks for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
As @Deepanshu katara mentioned you are using the wrong API version and also the error message says that you are missing the API version to the above shared resourceId at the end of the certificate name.
If you want to delete the certificate of App service, you can leverage the Certificates-Delete Azure Management Rest API.
Note :
- You can move a certificate bound to a web without deleting the TLS bindings, as long as the certificate is moved with all other resources in the resource group.
- If you are using free managed certificate in app service and if you want to move to another subscription, it is not supported as mentioned in this documentation as well.
Hope this helps, let me know if you have any further questions on this.