Cutting/Trimming an Orthomosaic GeoTiff Image

vps_dxb

I have a large orthomosaic tif file and I cannot for the life of me find a way to neatly cut the edges so that the image has clean lines around all borders.

I have tried setting the cropping options,, but I get a message about Collars popping up.
Tried selecting with the digitizer polygon, but when ending the selection it says no features were found in the selection!

Can it really be so hard to crop the edges of an image?

Thanks in advance!