Orange stains on/around silicone on new upvc windows?

Try upvc cleaner , leave it on the area for a few minutes then use a green Brillo pad to gently clean being careful not to damage silicon . If not unfortunately you may need to re silicone

You could try Pink Stuff Paste which is very effective with a light sponge scourer

Unfortunately, this will most probably be because the window reveal was not cleaned down and brushed off before the silicone / mastic had not gone off (cured) when brick dust or similar had covered / landed on it. You’ll never get the discolouration out of the silicone, only real way is to cut away / remove old sealant and have it redone, having window reveals thoroughly brushed down before applying new sealant. This is a job not many fitters like to do as it’s a nightmare to get old sealant off and always leaves a footprint on the reveal surface.

Avoid using solvent cleaners as sometimes they make things worse...sometimes. Just use a standard glass cleaner and a bit of elbow grease. If all else fails get in touch with a repair specialist such as myself and see if they can re-do the silicone around the windows for you. Staining can be caused by multiple things, such as smoking (usually the cause inside properties) or just general discolouration due to length of time that it has been on the windows or as someone has also mentioned, when windows were fitted and dust has accumulated.