Natural using Stack -> how to read and delete an entry

Hi, there.
I like programming using stack.
I want to read stack and, depending of the entry value, delete it.
I have found terminal commands documentation such as %.P and %.S.
Unfortunately, I haven´t found any example about it.
Please, do you know how to use stack to read or delete an entry ?
Thank you.

take a look at the SET CONTROL statement.

Once you issue SET CONTROL ‘%.S’, you use an INPUT statement to read the contents (you can use *DATA to see how many elements there are). Issue the SET CONTROL ‘%.P’ to delete the next entry on the stack (which, if you have just used ‘%.S’, will be the entry you just read).

Thank you Douglas for your detailed response.