The grammatically correct sentence is :

alors tu ne te bouches plus les oreilles

ne is often omitted in the spoken language when using the negation form.

ne plus literally means not anymore / stop.

My 2 cents :

    J'en veux = I want of it
    J'en veux plus = I want more of it (s pronounced)
    Je n'en veux pas = I don't want of it
    Je n'en veux plus = I don't want anymore of it (s non pronounced)