When you create a host pool and set its provisioning type as Template, you need to assign an existing template to it. This can be done when you create or modify a host pool, or you can assign a template to a host pool on the Templates tab.
To assign a template to a host pool:
Select a template and click Tasks > Assign to host pool.
Click Tasks > Assign to pool. A wizard opens.
On the Versions page, select the template version that will be assigned to the host pool.
(Optional) On the Host pool page, select the host pools that you want to recreate on schedule and click the Configure button. You will see a dialog that allows you to schedule recreation. Configure the schedule according to your needs and click Next.
Click Finish.
To remove a template from a host pool:
Select a template and click Tasks > Remove from host pool.
The Remove from Host Pool dialog opens listing all host pools using the selected template.
Select one or more host pools to remove the template from and click OK.
Note that if a host pool has hosts, they will be removed. You will see a message and need to confirm the removal.
If one or more host pools are being locked by another administrator, you will also see a message and will have to repeat the operation later when a pool is unlocked.