Some suggestions:
Buy a piece of hard brass bar stock, about 1/2" by 3/4" by about 6".
Shape one end to fit the sight closely but clear the slide.
Tape the slide sides to protect the finish, and have a buddy help hold the slide on a SOLID surface.
I have used a concrete floor or an anvil.
The idea here, is to get the slide in a SOLID, well-braced "no-bounce" position then use the brass bar stock and a hammer to push the sight out, from left to right.
Why many people, including gunsmiths have problems with sights and pins is, they just don't get the part in a firmly braced position, and the part bounces and moves, which dissipates the force of the blows. This can actually cause the pin or sight to rivet or deform, and can actually lock the part even tighter in place.
Most work benches are NOT solid and will allow things to move around.
The "Secret" is to do whatever needed to prevent bouncing or moving.
If you decide to cut, use a layer or two of a tough tape to completely cover the entire slide.
Next get some sheet steel, cut a hole in it that will just pass the sight, and wrap this around the slide.
The idea is to make a shroud, or guard covering EVERYTHING except the actual sight.
There should be as little of the area around the sight exposed as possible.
This will serve as a safety guard to prevent a run-away from damaging the slide. The tape will protect the finish from the steel.
You can also use sheet brass or copper.
If during the job you damage or displace the tape or shroud, STOP, and replace whatever is damaged or moved.
The problem is, many makers have had problems with sights failing to stay put.
The early Kahr guns sometimes had sights so loosely fitted that some of them fell out during shipping.
Kahr fixed this by fitting their sights so tightly, you often have to cut them out.
Kahr uses a massive modified machine vise to install sights at the factory, and they are so tight, they often can't be moved.
Good luck.