Hi @aurore.dehaene ,
Welcome to Microsoft Q&A platform and thanks for using Azure services.
As I understand from the question you want assistance in getting Migration of our IAAS VMS from AZURE SERVICE MANAGER to AZURE RESOURCE.
Please refer to the documentation Migrate your IaaS resources to Azure Resource Manager by March 1, 2023 which states necessary actions to be taken.
Regarding migration steps, we provide migration tool Platform-supported migration of IaaS resources from classic to Azure Resource Manager to migrate live VMs from Azure Service Manager to Azure Resource Manager.
If you have any additional queries regarding this retirement, please use comments to ask questions and we will try our best to answer those queries. Thank you.