You may have seen this article in the news recently, where a DIY amateur restorer decided to take it upon herself to restore a 120 year old fresco in her local church with rather disastrous results.

http://www.cbc.ca/news/offbeat/story/2012/08/22/fresco-ruined-woman.html

What may appear to be a simple treatment to the eyes of an untrained onlooker can often be far more complex than is realised. In addition to any practical work carried out, conservation takes into account the chemistry of the materials old and new and the ethics of the planned action before treatment is begun.

I hope that the painting can be removed but the wall, the old and new paint and the method of application will all have to be taken into account. Whatever occurs, unfortunately the painting will never be exactly as it was.