Hi Tahami Rizwan •,
Welcome to Microsoft Q&A forum and thanks for using Azure Services.
As I understand, you want to enable Azure SQL Managed Instance drop/deletion event logs.
I assume you have looked into this document https://learn.microsoft.com/en-us/azure/azure-sql/database/metrics-diagnostic-telemetry-logging-streaming-export-configure?tabs=azure-portal&view=azuresql-mi#basic-metrics which suggests to repeat these steps of diagnostic telemetry for each single and pooled database you want to monitor.
In addition to configuring diagnostic telemetry for a managed instance, you also need to configure diagnostic telemetry for each instance database.
Please check if it is already done. If done, please share configuration details of the SQL MI to further investigate.
Thanks