This works on the new facebook design.
To Leave the game completely.
1. Login to your account.
2. On the extreme right top right hand corner click on 'Account'.
3. From the drop down menu click on 'Application Settings'.
4. Beside Mafia Wars on the extreme right hand said you see the (X) mark
5. Click that and your done.
You can also try this method
1. Account
2. Privacy Settings
3. Click on edit your settings under "Applications and Websites"
4. Click on Remove unwanted applications
5. Choose the applications you want to delete and click on remove.
2. Privacy Settings
3. Click on edit your settings under "Applications and Websites"
4. Click on Remove unwanted applications
5. Choose the applications you want to delete and click on remove.
To Hide Mafia Wars notifications from appearing on your wall or News Feed
1. Locate the latest post from one of your friends account.
2. Locate the 'Hide' link on the very right hand side of the post.
3. You have two options. Either hide post from Mafia Wars software of hide posts from your friends
4. Choose what option you want and your done.
So if you only want to hide posts and not leave the game follow the last part of the answer. If you would like to leave the game completely then follow the first part of the answer.