Click the gear icon to find the “Delete” test option:

Deleting a test will clear all data and test variants associated with that test.
When you select to delete a test, you will need to tell our app if we should revert the product listing back to how it was when you started the test (Default Variant), or if you would like to leave the current test variant in place (Current Variant):

You can quickly tell which variant is currently in use by this indicator:
