Welcome to the forum.
Personally, I don't see that the sight modification is all that bad. Many guns were shooter modified and some folks enjoy collecting guns with such modifications. Remember, there are thousands of untouched plain Jane original guns out there but only a handful of guns that have been personally modified according to a shooters individual taste.
I am sure that a good gun restoration shop likes Fords in Florida could bring your gun back to original configuration if it really bothers you. No personal experience but I have seen much of their work and it is exceptional. Turn around time however may be an issue as I hear that they are very busy.
One other option might be to remove the red insert, square off the angled part of the sight and either leave it like that or you could add a Call bead to the riser. Bead front sights were very popular and don't jump out at you like the red plastic.
Your gun, your choice. Please let us know the end result and we will need photos or it never happened.
