Hi Sandeep,
Since record access is controlled through a users role the surest way to prevent users in a specific role from being able to edit and view a specific record is to add it to that roles edit and view permissions. For example if there is a specific record on a Company you do not want them to see you could go into your Participants role and edit their view permissions to be set to a custom rule so they can view all records that do not have the Company Name "Should Not Be Viewed Incorporated" or you could create a checkbox field that can be used to designate Admin Only records and set up non admins with a custom rule that they can only view records where the Admin Only checkbox is not checked. I hope this suggestion is helpful.
