If you want to delete or unpublish all items under a root item using PowerShell script then this is the post you are looking for. This script disables the 'publishable' option of an item in Sitecore.
This post would help you to remove the renderings of multiple items in Sitecore using Sitecore Powershell script. This will remove both Shared and Final renderings of the item.
This post would help you to change the template of some items programatically with Sitecore Powershellscript to a new template. It would actually change the templateId of the item using Powershellscript.
This post provides Sitecore PowerShell script to unlock all items locked in Sitecore by content authors.
Here is a list of Sitecore PowerShell scripts that are useful for every Sitecore developer for making any bulk changes in Sitecore.
A Sitecore PowerShell script to check if the selected sub tree of items have the language fallback enabled and update the items to enable the language fallback accordingly
This post gives details on what renderings are in Sitecore and different types of renderings available in Sitecore. This post also helps you to understand the concept of Layout and Placeholders in Sitecore
This PowerShell script can be used to clean or list all the Sitecore media library items which are not referenced by any item in Sitecore. This can also be restricted to a sub tree within the media library by updating the source path accordingly.
If you have encountered the error 'WARN Web Forms for Marketers: an exception The anti-forgery token could not be decrypted...' while submitting a WFFM form in Sitecore, then this could be the root cause and solution.
This post helps you to create a custom field validator in Sitecore. This involves creating custom validator class and validator rules/items in Sitecore.