Are you referring to the report that indicates how many reports is still unopened.
I'm not seeing a toggle to switch it off on map settings. But opening all unopened reports removes it.
However add a toggle somewhere I would suggest.
ok editing this : today received report that i traveled somewhere. Mmm the convention is to use a statusbar not a pop-up. Just add an option to toggle off pop ups with status tab below for those who do not prefer pop ups.