SharePoint Online: Delete Attachments from List Item using Powershell

Requirement: Delete Attachment from SharePoint Online List Item.

How to Delete Attachments from List Items in SharePoint Online?
To delete an attachment from SharePoint list items, Do the following:

• Navigate to the SharePoint Online List >> Select the List Item >> Click on Edit from tool pane.
• In Edit panel, scroll down to the bottom and click on little x Icon next to any attachment to delete it from the list item.
  
• Click on Save to commit your changes.

Delete All Attachments from a List Item using PowerShell:
Let's delete all attachments from a SharePoint Online list item using PowerShell.

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

#Set Parameters
$SiteURL= "https://crescent.sharepoint.com"
$ListName="Projects"
$ItemID="4"

Try {
    #Setup Credentials to connect
    $Cred = Get-Credential
    $Cred = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.UserName,$Cred.Password)
     
    #Setup the context
    $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
    $Ctx.Credentials = $Cred
 
    #Get the List & List Item
    $List = $Ctx.Web.Lists.GetByTitle($ListName)
    $Ctx.Load($List)
    $ListItem = $List.GetItemByID($ItemID)
    $Ctx.Load($ListItem)
    $Ctx.ExecuteQuery()
 
    #Get All existing attachments
    $AttachmentFiles = $ListItem.AttachmentFiles
    $Ctx.Load($AttachmentFiles)
    $Ctx.ExecuteQuery()
 
    ForEach($AttachmentFile in $AttachmentFiles)
    {
        $AttachmentFile.DeleteObject()
        $Ctx.ExecuteQuery()
 
        write-host  -f Green "Attachment File '$AttachmentFile' Removed from List Item!"
    }
}
Catch {
    write-host -f Red "Error Removing Attachment From List!" $_.Exception.Message
}

PowerShell to Remove Attachment from SharePoint Online List Item:

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

Function Remove-AttachmentFromListItem()
{
    param
    (
        [Parameter(Mandatory=$true)] [string] $SiteURL,
        [Parameter(Mandatory=$true)] [string] $ListName,
        [Parameter(Mandatory=$true)] [string] $ItemID,
        [Parameter(Mandatory=$false)] [string] $AttachmentFileName
    )    
    Try {
        #Setup Credentials to connect
        $Cred = Get-Credential
        $Cred = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.UserName,$Cred.Password)
    
        #Setup the context
        $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
        $Ctx.Credentials = $Cred

        #Get the List & List Item
        $List = $Ctx.Web.Lists.GetByTitle($ListName)
        $Ctx.Load($List)
        $ListItem = $List.GetItemByID($ItemID)
        $Ctx.Load($ListItem)
        $Ctx.ExecuteQuery()

        #Get All existing attachments
        $AttachmentFiles = $ListItem.AttachmentFiles
        $Ctx.Load($AttachmentFiles)
        $Ctx.ExecuteQuery()

        #Check if attachment file name exists
        $AttachmentFile = $AttachmentFiles | where { ($_.FileName -eq $AttachmentFileName) }
        If($AttachmentFile -ne $Null)
        {
            $AttachmentFile.DeleteObject()
            $Ctx.ExecuteQuery()

            write-host  -f Green "Attachment File '$AttachmentFileName' Removed from List Item!" 
        }
        else
        {
            write-host -f Yellow "Attachment File '$AttachmentFileName' Doesn't Exist!"
        }
    }
    Catch {
        write-host -f Red "Error Removing Attachment From List!" $_.Exception.Message
    }
}

#Set Parameters
$SiteURL= "https://crescent.sharepoint.com"
$ListName="Projects"
$ItemID="64"
$AttachmentFileName="ProjectProposal.docx"

#Call the function to copy list items
Remove-AttachmentFromListItem -SiteURL $SiteURL -ListName $ListName -ItemID $ItemID -AttachmentFileName $AttachmentFileName

PnP PowerShell to Delete Attachment from SharePoint Online List Item:

#Config Variables
$SiteURL = "https://crescenttech.sharepoint.com"
$ListName ="Projects"
$ListItemTitle = "SharePoint 2016 Upgrade"
$AttachmentFileName= "Project Proposal.docx"

#Connect PNP Online
Connect-PnPOnline -Url $SiteURL -Credentials (Get-Credential)

#Get the Context
$Context = Get-PnPContext
 
#Get the List Item from "Title" field value
$Query = "<View><Query><Where><Eq><FieldRef Name='Title'/><Value Type='Text'>$ListItemTitle</Value></Eq></Where></Query></View>"
$ListItem = Get-PnPListItem -List $ListName -Query $Query -PageSize 1
 
#Get List attachment by its file name
$Attachment = $ListItem.AttachmentFiles.GetByFileName($AttachmentFileName)

#Delete the attachment
$Attachment.DeleteObject() 
$Context.ExecuteQuery()