Creo Layout > References > Data Management > Setting an Object as Read-only
  
Setting an Object as Read-only
Click File > Lock File in an active session to set an object as read-only . Read-only status is a property of the local cache and not the server side workspace. When an object is locked, geometry creation tools are not available. For more information on setting an object as read-only, search the Data Management area of the Help Center.