Nodes and Nodegroups
Nodes are organized in nodegroups. If you want to create new nodes or delete existing ones you have to resize the nodegroup. The nodegroup defines which flavor will be used for new nodes.
To resize a nodegroup select the "Nodegroups" tab and click on the "Resize" button in the context menu. Note that it is not possible to resize the master nodegroup. Select the desired node count and finally click on "Resize Nodegroup".
A cluster has two nodegroups by default. The master nodegroup and the default nodegroup. You can't delete these nodegroups. In the case of the default nodegroup it is possible to scale the node count to zero, though.
To create a nodegroup click on the "Create Nodegroup" button and customize the new nodegroup to your wishes.