The e2e tests have a cleanEntities function that should ensure that everything is cleaned up between test runs and created reports and dashboards are deleted again: https://github.com/camunda/camunda-optimize/blob/12ea5ad70b3704db7641d663d1db6fbb9b48749b/client/e2e/setup.js#L42-L54

However, the endpoint that this function uses does not exist anymore (there is no /api/dashboard to get all dashboards) as it has been moved to a more generic /api/entities endpoint.

Deletion must still be done in the /api/dashboard space.