A review can be deleted by the person who created it. You can do this from the More options menu (three dots) next to the review name in the main menu, or on top of the Overview page.

From the same menu you can archive your review. Archived reviews can be restored.

Members of a review can be removed by the review owner. You will find the Review Members on the Overview page. Click on the three dots to the far right of the person's name. The menu gives you two options:

Delete member. The member is removed from the review, and their contribution to the screening disappears.
Revoke member. Requires a paid subscription. The member loses access to the review, but their coding remains, and access can be restored.

You can change people's roles by clicking the arrow next to their current role.