The only way to downgrade AFAIK is to Build older versions of the engine from source. Epic have older version repo’s on their GitHub page which you can download and Build with Visual Studio. If you are using any Plugins from the Marketplace though, you will not be able to associate those with the source build, which was the deal breaker for me… (There probably is a way to get Plugins working with source builds but its ridiculous to have to go through all of these steps just to downgrade).