Get and Renaming SPFolder c#

This is how you can rename a SPFolder. There is no need to use MoveTo() as suggested by others.
The user has to have rights to do it, or enclose the whole thing inside a

var siteId = "Guid of my site";
var webUrl= "Server relative path to my web";
SPSecurity.RunWithElevatedPrivileges(delegate(){
    using (SPSite elevatedSite = new SPSite(siteId))
   {
       using (SPWeb elevatedWeb = elevatedSite.OpenWeb(webUrl))
      {
          string requestFolderUrl = webUrl+ "/MYLIST/OldFolderName";
          SPFolder requestFolder = elevatedWeb.GetFolder(requestFolderUrl);
          if (requestFolder.Exists)
          {
               requestFolderItem[SPBuiltInFieldId.Title] = "NewName"; //not really needed for renaming
               //requestFolderItem[SPBuiltInFieldId.BaseName] =  "NewName"; //this Fails.don't know why
               requestFolderItem["BaseName"] =  "NewName"; //this Works!
               //don't want to update the Modified time nor the modified by Info
              //If you want to modify this info use Update, and avoid being in a RunWithElevatedPrivileges
             ///because else you would have the System User registered
               requestFolderItem.SystemUpdate(false);
           }
      }
   }
}

Remove Event Handlers from SPList Powershell

This is how you can  delete Event handlers from a SPList

$webUrl= "http://yoursite.com/subsite"
$listName = "myList"

$site = Get-SPSite($siteUrl)
$web = $site.OpenWeb()
$listWithEventHandlers = $web.Lists[$listName]

#you can find out the index of the eventhadler through a selector, or just beeing lazy
#and loop the eventhanlders


 $allEvenReceivers  = $list.EventReceivers
foreach($ev in $allEvenReceivers  )
{
   write-host $ev.Name;
}
$index = 0
$eventHandlerToDelete = $listWithEventHandlers.EventReceivers[$index]$eventHandlerToDelete.Delete()
$listWithEventHandlers.Update()

$web.Dispose()
$site.Dispose()

Access MasterPage catalog with Powershell

To acces the Masterpage catalog via Powershell, and then use it as a list the following script might help

if(-not(Get-PSSnapin | Where { $_.Name -eq "Microsoft.SharePoint.PowerShell"}))
{
    Add-PSSnapin Microsoft.SharePoint.PowerShell;
}

clear
$siteUrl = "http://yourserver.com"

$masterPageCatalog = "_catalogs/masterPage"

$site = Get-SPSite $siteUrl

$rootWeb = $site.RootWeb;

$folder = $rootWeb.GetFolder($masterPageCatalog)

$masterPageCatList = $rootWeb.Lists[$folder.ParentListId]

#do some list operations on it


$rootWeb.Dispose()
$site.Dispose()