Hi @Victor ,
Thankyou for using Microsoft Q&A platform and thanks for posting your question.
As I understand your issue, you are trying to delete the event based trigger which was pointing to a storage location that's no longer in place and is leading to the above stated error. Please let me know if my understanding about your query is incorrect.
I would recommend you to check and make sure that the following permissions are granted :
- The synapse workspace managed identity and your active directory Id has Contributor access to the event grid subscription.
- Event grid resource provider has been registered in the subscription level.
Please let me know if the above solution helps. Looking forward to your response. Thanks.