The way you'd usually do it is either having a multi-user application and just create a new user for a new test (also helps testing concurrently) or you'll have to reset the app by:

- redeploying it on a new e.g. EC2 instance

- clearing out the database and inserting your original blank state from an SQL dump

- clearing out the filesystem by e.g. using a git reset

p.s. you should try to have an automated deployment for your product. That way you could also just spin up a new EC2 instance -> deploy -> test -> kill instance