Simply deactivating Content Organizer Feature won’t help in deleting the Drop Off Library.
Execute the below PowerShell Script and get the job done:
Solution:
$url = "http://<siteurl>/"
$feature = Get-SPFeature "DocumentRouting"
$site = New-Object Microsoft.SharePoint.SPSite($url)
foreach ($web in $site.AllWebs)
{
if ($web.Features[$feature.ID])
{
Disable-SPFeature $feature -Url...