Posting the answer on behalf
@Hanh Trinh
to benefit others looking for solution to a similar issue.
Get-AzResource -ResourceGroupName $resourceGroupName -TagName "CreatedBy" -TagValue "AzureBackup" | foreach{
if($_.ResourceType -match "Microsoft.Compute/snapshots"){
$name = $_.Name
$snapshotupdateconfig = New-AzSnapshotUpdateConfig -NetworkAccessPolicy DenyAll
Update-AzSnapshot -ResourceGroupName $resourceGroupName -SnapshotName $name -SnapshotUpdate $snapshotupdateconfig
Hope this helps!
If the response helped, do "Accept Answer" and up-vote it