You may remove the Site System itself!
Remove-CMSiteSystemServer -SiteSystemServerName $dp -SiteCode $site -Force -ErrorAction SilentlyContinue

The only thing missing is the maintainenance of the orphaned Library on the uninstalled DP ..

I think about creating an CMScript an run the CMScript for deleteing the share and folder of the Content Library after uninstalling the dp role …

This wasn’t reliable for me but after a little tweak this ran through 220 DP role removals:

<#

.SYNOPSIS

Remove Distribution Point role using PowerShell Script

.DESCRIPTION 

This scripts lets you uninstall SCCM Distribution Point

.PARAMETER DistributionPoint

This is the server name from which you would be uninstalling Distribution Point role.

.PARAMETER SiteCode

This is 3 letter site code.

.NOTES

Version: 1.0

Published Date: 10-Dec-2016

Updated Date: 21-Apr-2020

Author: Prajwal Desai

Website: https://www.prajwaldesai.com

#>

#Load the Configuration Manager Module

import-module ($Env:SMS_ADMIN_UI_PATH.Substring(0,$Env:SMS_ADMIN_UI_PATH.Length-5) + ‘\ConfigurationManager.psd1’)

$Drive = Get-PSDrive -PSProvider CMSite

CD “$($Drive):”

#Site Code and Distribution Point Server Information

$SiteCode = ‘ABC’

$CSVin = “path to csv file”

#Get the content of the CSV file

$Computers = Get-Content -Path $CSVin

#Loop through each Device and perform actions

Foreach ($Name in $Computers){

  #Check if the DP server is alive

  Test-Connection -ComputerName $Name -quiet

  #Remove Distribution Point Role

  write-host -ForegroundColor Green “The Distribution Point Role is being uninstalled on $Name”

  Remove-CMDistributionPoint -Force -SiteCode $SiteCode -SiteSystemServerName $Name

} 

#Site Code and Distribution Point Server Information

$SiteCode = ‘IND’

$CSVin = “C:\Scripts\Remove-CMDistributionPoint\RemoteDP.csv”

#Get the content of the CSV file

$Computers = Import-Csv $CSVin

#Loop through each Device and perform actions

Foreach ($Computer in $Computers) {

  #Check if the DP server is alive

  Test-Connection -ComputerName $Computer -quiet

  #Remove Distribution Point Role

  write-host -ForegroundColor Green “The Distribution Point Role is being uninstalled on $Computer”

} 

This question is in reference to the Site System role that SCCM removes on its own after a period of time.You are not able to remove it by design.

BTW, there is a space after the lesser than sign. I changed:

< #.SYNOPSIS

to:

<#

.SYNOPSIS

Can you be more precise on what exactly you want to remove or uninstall ?.

What if we are trying to discontinue/uninstall permanently offline DPs?
Is the same procedure applicable?

Regards