15.5.832 zap

zap, var1 [, var2, …] [, /pointer]

Completely removes the listed variables (except for function pointers). Afterward, it is as if they never existed. If a (function) pointer is zapped, then the corresponding variable, subroutine, function, or blockroutine, and all associated variables and executable code, get zapped. To zap a (function) pointer itself, add the /pointer key to the zap call. zap cannot be used inside a user-defined subroutine or function.

See also: delete, pointer