Google has suggested in a Google Webmaster Help thread, it is better to start a new website if your current website has been charged with a severe penalty. Google's Webmaster Trends Analyst, John Mueller mentioned it again this week in a Help thread.
This advice was given to a website which has been penalized and has several other websites all with penalties associated with them. Mueller said at times when the issues are severe and you are sure you know the correct method to follow; it is advisable to delete the old sites and create one new website. It is difficult to take such a big decision but if you are certain that you can avoid all the issues associated with the current site like the problem of unnatural links and you have a well written content, then reviewing is a better option.
For example, if there are unnatural links on the website, it is a webspam issue and anything related to the website will not be easily trusted. In that case, it is always better to start afresh and create a new website. Mueller had also posted earlier on Google+ and Google Webmaster Help thread to start afresh a new website rather than trying to fix all the issues with the current site individually. Google’s head of Search Spam, Matt Cutts, has also advised time and again that digging your website out of a spam hole is more difficult than starting a new website.Google Suggests Websites with Serious Penalties Should Start Afresh and Create a New Website!,