Disable Creation of New Folder in Existing Document Libraries

Scenario:
You have a SharePoint farm with many Site collections and document libraries. You have decided that you want to disable the creation of new libraries in all Document libraries. 

Solution:
You could manually edit the settings of every library or you could run the below PowerShell script:

Add-PSSnapin Microsoft.SharePoint.PowerShell

#If you know the site URL that you want to affect just change $sites to "Get-SPSite "http://{siteurl}" otherwise all sites will be affected

#Get list of sites in the farm

$sites = Get-SPSite -Limit All | Get-SPWeb -Limit All

#Get list of document libraries in the farm and remove system folders from the list

$folders = $sites.folders | where {($_.name -ne "FormServerTemplates") -and ($_.name -ne "Style Library") -and ($_.name -ne "SiteAssets")}

#Get a list of document librarys that are actual document libraries and not catalogs etc...

$items = $folders.properties | where {$_.vti_listservertemplate -eq "101" }

#Grab the title of the remaining libraries

$libs = $items.vti_listtitle 

#Remove duplicate items from the list

$itemsclean = $libs | select -Unique

#Run through the list of libraries

foreach($i in $itemsclean){

Write-Host "Changing Library " $i   

$list = $sites.lists | where title -eq $i

#Set the folder creation value to false   

$list.EnableFolderCreation = $false

#Update the value  

$list.Update()   

Write-Host "Changed " $i

}