Salutation field is Mandatory and cannot be removed from the Layout.
Middle Name and Suffix can be disabled by following these steps:

• Click Setup || Customize || User Interface.
• In the Name Settings section, deselect Enable Middle Names for Person Names and Enable Name Suffixes for Person Names.
• Click Save.

The Middle Name and Suffix fields are available for the following person objects: Contact, Lead, Person Account, and User.

The values of the Middle Name and Suffix fields appear in most places where a person’s full name is displayed with the following exceptions.

• Activities, including new events, new tasks, and shared activity lookup search results
  Calendar, including meeting invitations and the Scheduled Meetings section on the Home tab
• Campaigns, including Campaign Member lists
• Chatter
• Cloud Scheduler
• Data.com records
• Forecasts, including the Collaborative Forecasting page
• Opportunities, including opportunity stage history, the Opportunity Sharing Detail page, and the Opportunity Split Edit page
• Price Books, including price book history
• Recycle Bin
• Search results for users