Phrase translation

I've been researching meticulously to translate this phrase into either Quenya or Sindarin: "Don't let go" or "Don't you let go" I've gathered a few different possibilities, but what hoping I could get some other insight.

Hi Moriah, and welcome to Parf Edhellen!

I would propose that you use vá in conjunction with lerya-: valye lerya! "you mustn't let go!" or simply vá lerya! "don't let go!"

The Sindarin translation would be:

Avo leitho!