In order to be able to delete all Azure managed disks that start with mydisk, for example, you’ll first need to run the Azure Bash shell instead of PowerShell and then type:
az disk list --query "[?starts_with(name,'mydisk')].[name]" | xargs -L1 bash -c 'az disk delete --resource-group yourresourcegroup --name $0 --yes'
In order to view all managed disks that start with the disk name, type:
az disk list --query "[?starts_with(name,'disk')].name" --output tsv