How to free memory after required modules

There may be a misunderstanding. I want to free memory.
Starting with this:

var g = require("ILI9341").connect(SPI2,C6,C7,C8,function(){g.clear();});

Process.memory() returns usage 329
Dump shows var g = { ..... digitalWrite(C6,1....
Result is as expected

g = "";

Process.memory() returns usage 331
dump shows var g = ""; digitalWrite(C6,1.....
I expected less memory usage

Modules.removeAllCached(); 

Process.memory() returns usage 330
dump shows var g = ""; digitalWrite(C6,1.....
I expected less memory usage
Tried to do this:

var b = "ILI9341";
g = require(b).connect(....

returns unable to read file no path
Process.memory() still returns usage 332
There is no object, no module, so how do I get rid of memory consumption ?