How to clear all security class access information

@Native

I want to clear all security class access information. I tried set 'None' access to all users and groups for all security classes, but its not same as clear - if I export security class access information to .sec file I see a lot of lines like this:

SecurityClass1;User1@Native Directory;None;N

SecurityClass2;User1@Native Directory;None;N

SecurityClass3;User1@Native Directory;None;N

SecurityClass4;User1@Native Directory;None;N

SecurityClass5;User1@Native Directory;None;N

...

SecurityClassNNN;User1@Native Directory;None;N

...

SecurityClass1;User2@Native Directory;None;N

SecurityClass2;User2@Native Directory;None;N

SecurityClass3;User2@Native Directory;None;N