Discussion on the Internet indicates that, depending on the year of manufacture, Pietta Remington front sights were screwed in or pressed in, with or without the use of silver solder, Loctite, or epoxy. VTI Gun Parts shows a replacement sight that is not threaded. The target (Tiro) version has a dovetailed sight.
If your gun has a dovetailed sight, it should be obvious. If not, what I would do, first, would be to carefully try to unscrew it. Use a pin vise or hand-held drill chuck to clamp the sight. If it doesn't come out easily, then heat the muzzle area of the gun cherry red with a MAPP torch, to melt the solder. While the solder is still molten, try unscrewing it again. (This should also work with Loctite or epoxy, or with a pressed-in sight.) If this still doesn't work, then the only thing left is to cut off the sight, file a dovetail in the barrel, and install an Uberti-type dovetail front sight. You have to decide how far you want to go with this. Sometimes it's better just to leave well enough alone. (Heating the muzzle will mess up the bluing, for sure.)