This feature is available in all editions.
Go to Product Planning > Regression Tests.
Select the regression test you want to delete, and then select Delete from the Edit drop-down list.
In the pop-up window, click Delete. The test will be permanently removed from the system.
You can delete multiple tests simultaneously. Select the checkboxes to the left of tests to deleted, and then choose Delete from the Move to Project drop-down list, then click Delete on the Delete Items page.