You can have a smith grind off the single-action notch from the hammer--probably best left to a professional, though people here no doubt have done it.
If by still having single-action capability you mean you can pull the trigger far enough to gain purchase on the bobbed hammer and cock it, that's risky, but you probably know that.
Personally I'm kind of mistrusted in some circles here for saying that I don't want single-action capability on a self-defense revolver because it's too easy under massive adrenalin rush to touch off a shot you don't want to fire. But that's my story and I'm sticking to it. I'm old, inept and cantankerous.
^^^+1 to what Shouldazagged said. (Except the old part. )
I've ground off the SA notch and wasn't to hard but you need a steady hand. If you want some help PM me your email address I can help walk you through it.
As long as you don't make a deliberate effort to cock the revolver for single-action it will work perfectly well in double-action and no one would know the difference. It still preserves the option of single-action when desired. Removing the single-action notch provides no advantage whatsoever.
My three J frame 38s all have bobbed hammers and will still engage
single action. This hurts nothing and gives you the option of a bit of
single action plinking if you so desire.
I have a M1917 .45ACP with a bobbed hammer and shortened bbl. with single action unmodified. It shoots fine dbl. action and is a hoot to shoot, but still can be cocked single action if you choose and works fine that way. the only problem is pulling the trigger a little bit to allow you to catch the hammer and cock it. I don't see any reason to worry with the single action notch.
Take it to a gunsmith and have him take care of it. Do not carry this weapon for self-defense until you get it done. This configuration might prove to be a huge liability legally if you did use it in self-defense. It is irresponsible and unsafe to try and use it in single action in this configuration . J-frames are not target guns or plinking guns, they are close quarter self-defense weapons and great carry guns. You do not need single action on any self-defense revolver let alone on a j-frame in this condition.
If you want a j-frame for self-defense(I don't know what other reason you'd otherwise pick one), I'd strongly suggest you get a centennial model. Hammer Or? ?-Less?? | Guns Magazine