tt(POPWSLEVEL) is used to remove the topmost wslevel from the wslevel stack.
The values of wslevels may be pushed on a stack using
lref(PUSHWSLEVEL)(PUSHWSLEVEL). See also section lref(DECWSLEVEL)(DECWSLEVEL)

To remove the topmost element of a wslevel's stack tt(POPWSLEVEL) is
available. tt(POPWSLEVEL) expects one argument: the name of the wslevel to
pop. The previously pushed value then becomes the new value of the wslevel. A
wslevel's value may be popped after defining it, emptying the stack, but the
wslevel will still be defined. In that case, using the wslevel's value is
considered an error.

    Example:
        verb(
    COMMENT(Assume WS level is zero)
    
    PUSHWSLEVEL(1)
    COMMENT(WS level now equals 1)

    POPWSLEVEL()
    COMMENT(WS level now equals 0 again)
        )

