This script will search AD for any computer objects that match the OperatingSystem value of Windows 7. It will then disable those systems and move them to a container called “To Be Removed” at the root of the domain.

The second part imports your SCCM module, mounts the drive and then removes those same objects from SCCM.

# To View Windows 7 Systems
Get-ADComputer -Filter {OperatingSystem -Like "*Windows 7*"} -Property * | Format-Table Name,OperatingSystem,Description,Enabled,DistinguishedName -Wrap -Auto

# Gather Windows 7 Systems
$win7systems = Get-ADComputer -Filter {OperatingSystem -Like "*Windows 7*"} -Property *

# Disable and Move to Disabled Computers
foreach ($system in $win7systems) {Set-ADComputer $system.Name -Enabled $false; Move-ADObject $system.DistinguishedName -TargetPath "OU=To Be Removed,DC=DOMAIN,DC=DOMAIN,DC=TLD"}

# Remove from SCCM
# Site configuration
$SiteCode = "SITECODE" # Site code 
$ProviderMachineName = "SCCM SERVER ADDRESS" # SMS Provider machine name

# Import the ConfigurationManager.psd1 module 
if((Get-Module ConfigurationManager) -eq $null) {Import-Module "$($ENV:SMS_ADMIN_UI_PATH)\..\ConfigurationManager.psd1"}

# Connect to the site's drive if it is not already present
if((Get-PSDrive -Name $SiteCode -PSProvider CMSite -ErrorAction SilentlyContinue) -eq $null) {New-PSDrive -Name $SiteCode -PSProvider CMSite -Root $ProviderMachineName}

# Set the current location to be the site code.
Set-Location "$($SiteCode):\"

# Remove SCCM Objects
foreach ($system in $win7systems) {Remove-CMDevice $system.Name -Force -ErrorAction Ignore}