Here is a quote from the documentation
Julia does not have an analog of MATLAB’s clear function; once a name is defined in a Julia session (technically, in module Main), it is always present.
If memory usage is your concern, you can always replace objects with ones that consume less memory. For example, if A is a gigabyte-sized array that you no longer need, you can free the memory with A = 0. The memory will be released the next time the garbage collector runs; you can force this to happen with gc().
Is there a reason for this? The proposed workaround,
A = 0, has the problem that if I attempt to use the variable
A at a later point, there will be no error, which can be unsafe when my intended behaviour wast to clear the variable to prevent its future use.