Hello,
You can uninstall new Outlook from Windows Settings > Apps > Installed Apps.
As for Classic Outlook, it is not a free app. If you want to use it, make sure you have Microsoft 365 personal or family or premium license already. If you do a search of Outlook from the search box on yoru taskbar, and if Classic Outlook is not there, you can download and install it from here: https://support.microsoft.com/en-us/office/install-or-reinstall-classic-outlook-on-a-windows-pc-5c94902b-31a5-4274-abb0-b07f4661edf5