EGOvoruhk said:
This is for PC, not a TV. I use MPC-HC with madVR/NNEDI3 for most video playback, I’m not aware that I can remove the black bars.

MPC-HC can be used to easily crop/scale to remove the letterboxing. There are two ways of doing it, you will have to decide what is best as I don’t have an ultrawide to test. In the context menu > video frame > touch window from outside. Or alternatively context menu > Pan&Scan > Zoom to UltraWidesreen. As far as I can tell the first option should be better?

EDIT: it seems you might have to Zoom to Widescreen rather than to UltraWidescreen