If you want to try the new Dynamics 365 Business Central please login into https://trials.dynamics.com/, and you just need to provide your work email address and Phone No.
If you already have signed up previously then, on login it will redirect you to the Finance and Operations Business Edition and to reset to Business Central you need to follow the below steps. Once you login, Go to your Apps and Select the Financials App for the production instance,
Choose the icon, enter Sandbox Environment, and then choose the related link.
In the above screen you need to Reset the Sandbox Environment.It will take a minute or two to complete the process and might show up an error screen at the end but don’t worry, you just need to logout and re-login which will reset your environment to the new Business Central Edition as shown below
If you have any other Tips or suggestions, please do share them in the comments below.