Hi Damien Doumer •,
Welcome to Microsoft Q&A forum.
As I understand, you could not delete Azure Database for MySQL Flexible Server as it gets timed out.
Please try below ways and see if this helps:
1). Try to Stop server first and then perform Delete operation as when the Server is at Start mode, there could be management operations going on the backend which could block he deletion operation.
2). Try to perform delete operation using Azure CLI/Powershell.
For deletion of flexible server:
az mysql flexible-server delete --resource-group testGroup --name testserver
For deletion of database in the server:
az mysql db delete -g testgroup -s testsvr -n testdb
https://learn.microsoft.com/en-us/cli/azure/mysql/db?view=azure-cli-latest#az-mysql-db-delete
Let us know if this helps.
If not, please share configuration details. network settings, region etc of your server so that we can investigate.
Thanks