For more details on uninstallation, see Uninstall Adobe Premiere Elements or Photoshop Elements.
Windows: go to install location and check for the application. If the application is present, delete the folder.
macOS: open Finder and navigate to Applications and check for PSE or PRE. If the folder is present, delete it.
If you have the application setup, launch and run the application. If you do not have application setup, download, install, and launch the application.
To reactivate the application, enter the serial key. For more information, see Find the serial number of your Elements product.