have a child while parent is not accesible

[C# Programming]

hi, i apologize for asking this simple question
but i should ask it because i am not familiar with the terminology to search in the internet
i want to have a child form, and i know how to do it
but i don't want the parent form be accessible when the child exists
please tell me what can i do?

here is the code i used for my child form

Form2 myChildForm = new From2();
myChildForm.MdiParent = this;
myChildForm.show();