Please note, V5 is currently not supported in on-premise environment.
Should you need or want to revert back to V4 of Page Designer, follow the below steps for successful uninstallation of V5 and re-installation of V4 in your Site Collection.
Step one-Navigate to Site Contents
Scroll or navigate to the LiveTiles Designer Manager and click, you will be directed to the Designer app
Step two- Uninstall LiveTiles Design Pages
From here, scroll down to the Deploying Designer to Site section, the first item under that section will be: LiveTiles Design Pages
Click the uninstall next to it
You will notice the spinning circles as the item updates
Step three- Install Designer
Now that LiveTiles Design Pages are uninstalled, you will have to Install Page Designer again. Scroll back up and click Install
After successful install, you will be prompted to Go to LiveTiles Design
When clicked, you will be redirected to the Landing Page in V4
You will still have the option to upgrade to V5 from the Landing page or in Design view from one of your pages
No content from existing pages, templates, sections, tiles, will be deleted by reverting to V4 or upgrading to V5.