There are two locations in Service Center where you can exclude on a per device basis; from the Onboarding Overview dashboard and from the Device Overview page.
To exclude a device when onboarding a site
In Service Center, click Status > Onboarding Overview.
Click the site that contains the device you want to exclude.
Select the check box beside the device you want to exclude.
Click Exclude Device.
To exclude a device when viewing device details
In Service Center, click Status > Devices.
Click a device name.
Click Exclude Device on the right sidebar.