I have a BRU-EWR flight coming up that connects in FRA. I'm thinking of going from BRU-FRA a day early, but I haven't tried calling United to have that leg cancelled (if that's even possible), and I can't seem to locate an option to do that under my itinerary.

My question is, will I run into any issues if I simply skip my BRU-FRA leg and arrive on a separate flight the day before? I am not an EU citizen, so I will need to clear customs as well. Just trying to think this through. I would then keep my FRA-EWR flight as-is.