Use the ACS tools AEM fiddler tool, change the script to servlet from
header ,in your servlet, get all the assets from the folder in dam and
use the moveAsset method of AssetManager api to move assets from one
location to other.AssetManager ("The Adobe AEM Quickstart and Web
Application.") Eg: // To move Asset from /document/somedocument.pdf to
/document/legal with name document.pdf
AssetManager#move("/document/somedocument.pdf",
"/document/legal/document.pdf");