Reports - use of slicers

A former colleague created a report for the organization before he left, and we have to make some changes. In that process, I’ve a few issues. Is it correct that you cannot use slicers in the report, and likewise cannot filter on a hierarchy included in the report? My former colleague added a slicer himself, but I simply cannot get it to work. At first, I thought something was layered on top of it and “blocking” it, but even when it’s placed at the front, I still can’t click on it. Is that standard  or an error?

Additionally, our users are asking whether it is possible to remove the box 'Vis eksempel' in the bottom-left corner.