There is a common metaphysical concept: Everything that has every been imagined is real.
So, if this is true, gargoyles and entities exists. Being someone who has taken the time and done the work to open psychic awareness, I’d say from my experiences many of these things do exist. In fact, I’d say reality is highly populated with these types of things.
But, much of this stuff exists on other dimensions/frequencies – levels of reality which most people are blind to. But some people with heightened psychic sensitivity can sense/see things bleeding in from these other dimensions.
As far as getting rid of entities or helping other people with these things, I suggest training. Don’t try to do it on your own without proper knowledge of how to deal with things. You can get yourself in trouble quickly. I say this from personal experience.
We offer training here (Life Mastery Program) and there are other places where you might be able find help with this. Be careful about books, as this can be an incomplete path. Hope this helps!