There's currently no functionality available to exclude these. Some users do want to include these in the report for investigation purposes, this way the report gives a full overview of all outages. They are grey'ed out to make it clear that they have no impact.
If you really want to get these out of the report, this could be achieved by creating a custom legacy report.
We're also planning to get this SLA report in the new Dashboards app through GQI.