That's a magazine disconnect, so the gun won't fire without a mag in it. I have no idea if it can be disabled without affecting the function of the action. Nor would I encourage anyone to do that. If you really dislike that feature, sell it and buy a different gun.
One thing about it though, when the gun is empty and no magazine in it, if you cock it you cannot de-cock it without inserting the magazine back into it. I have tried all the usual methods and none seem to work. Is this the way it is made