I believe it is possible to have something removed but you would have to prove it was factually incorrect (eg not just a differing opinion) and probably that it was harmful in some way - say to your reputation. They do not belong to you. If your medical records are computerised then you have had the right for many years, through the data protection act, to request a copy. I believe that this may have been recently extended to include written notes with some restrictions. Contact your local health authority and ask. Also this link gives you some info:
http://www.cfoi.org.uk/persfilesintro.html