How do I disconnect a host in order to delete it?

Elastic Orchestration Elastic Cloud Enterprise (ECE)
1

Hi there, I want to delete a host.
I am following the documentation.
In the ece GUI I could now push the button: Manage host -> delete host
Then comes the popup: Delete Host?
The button is grayed out and I get the following text: 'Disconnect this host before deleting it.'

How do I disconnect a host?
cheers
steman

2

...does it mean, run this:
docker rm -f frc-runners-runner frc-allocators-allocator $(docker ps -a -q); sudo rm -rf /mnt/data/elastic/ && docker ps -a
....and then click the botton / button gets active?
At least this is what worked for me.
cheers
steman