What is the use of the Check G/L Account Usage

ameen

Help says :

If selected, the program prevents G/L accounts that are used in setup tables, such as posting groups, from being deleted.

I created a general business posting group and assigned to one account.

I place acheck mark in that fields. Check G/L Account Usage
Now I want to delete that posting group. When I press F4 it deleted, that what is the use of this field.

Deep

You should read the online help carefully.
It talks about not deleting the G/L account if it is used in the specified posting groups, but not about deleting a posting group.