Is the sentence "It is removed" grammatically correct?
It is removed is grammatically correct, but is not something people normally say. It sounds quite stilted.
The only context I can think of would be as a reply from a "right hand man" to his boss, if the right hand man was particularly well spoken:
Boss: This room is too cluttered. Remove this obelisk.
RHM: Yes sir.
(RHM gestures to minions. Minions remove the obelisk.)
RHM: It is removed.
A much more common idiom is it is [far] removed from X which implies the thing that it refers to is [very] different to X.
E.g.
This chaise longue is far removed from the stools of your hovel, eh?