Remove the Full Access privilege set

To ensure that users can't gain access to parts of the custom app and schema that only they would normally have access to, use FileMaker Pro to permanently remove the Full Access privilege set from the file.

Important  Removing the Full Access privilege set permanently deletes from the file all accounts that were using the Full Access privilege set. This permanently eliminates access to Layout mode and the Script Workspace. Access to the Manage Security dialog box is also eliminated, unless you have other accounts with the Manage extended privileges or Manage accounts that don't have Full Access privilege enabled. Schema and design elements of the files cannot be recovered. The only way to modify the tables, field definitions, relationships, scripts, or all access privileges is by returning to the original file before the Full Access privilege set was removed.

See "Removing Admin access to databases" in FileMaker Pro Help.