Blocked Fire Place Vent ??

We rent a 1960's bunglaow that has a fireplace thats been blocked up & not used since 1970's but has an ugly looking vent. The vent has been hidden by various pieces of furniture in the past but i now wish remove furniture away from this wall. The walls have paper lining.

Can i cover this vent & make good without having to have the wall re-lined ??

I think fireplace vents are usually there to prevent damp in the chimney. You're not really supposed to block them if you still have a chimney....