sure you can. The easiest way to do this is to allow HCS to manage the deletion for you. this will tidy up all objects created from your azure subscription as well as deleting the node records in the cloud service
To do this, go to Settings->Capacity and select the node you wish to delete, to drill into the node deletion page
From there, click Delete. it will then prompt you to type in the node name to prove that you are sure you want to perform the deletion.
in the example above, type (or copy paste) node390 into the box and click delete. Do note that this will delete the node, Access Gateway, and any images/pools, and any active sessions will be deleted. ie make sure end users are not using the system.
When you come to add back a node, you can add the node, and reuse the existing azure subscription service principles, or add a new one. From there you can select the same, or a different region. Remember that if its a new region then to make sure you have sufficient quota headroom for the various vm family sizes, and remember you will need to set up a VNet/AD/DNS connectivity in that region.
I know this doesnt apply to you - but if you were building out a node and realised you had made a mistake, then the getting started page does have a button allowing the node to be deleted too, this allows you to quickly delete and startover.
Do note however in all cases that the resources are deleted from Microsoft Azure. Whilst this is automated, it can be slow-ish... we have seen this take 15-20 minutes (or more) and this is based on the load in the Azure environment at the time. If you want to create a new node reusing the same network address ranges then you would need to wait for the deletion to fully complete before you can add the new node. You can watch the deletion progress in the azure portal.
hope that helps,
thanks. hadn't spotted that in the ui.