destroying an object in javascript -

this know quite basic one, but, please tell me how can destroy object in javascript, created dynamically.

actually have created instance of nicedit javascript text editor, , after taking user's input in , saving entered text, want destroy it.

here's snippet of code im using create instance:

    myniceditor = new niceditor(); 

here nicedit variable global.

and here's how im destroying right now:

    myniceditor = undefined; 

inside function. but, not deleting. know b'coz when create instance using same variable name, i'm able see last entered text, has saved internally.

plz help..

just @ documentation, stated clearly.