I have read you can simply delete the upgrade folder to downgrade but some people mention you must restore a older database or it wont properly work. Can someone verify this? Do I need to import a older database backup that pertained to the same version of Concrete5 to downgrade?
You also need to go to config/site.php and delete the line that indicates the update folder
Your site's database schema needs to match the concrete5 core you're using.
When one removes an upgrade folder (and also removes the DIR_APP_UPDATED setting in config/site.php), the database will remain set up to work with that new version of concrete5. Often you'll see problems (PHP and mysql errors) immediately when a concrete5 component trys to find a database table or run a php function that doesn't exist in the older version of the core.
The only practical way to "roll back" to a previous version is to import a database backup.
Here's a how-to article on figuring out a database / core mis-match:http://www.concrete5.org/documentation/how-tos/developers/troubleshooting-concrete5-updates/