Despite its title, the poem doesn't give orders so much as make a quiet, tentative request. The speaker is writing in a green book, and what they write are two small phrases: "no" and "let me be." Together they sound like a refusal and a plea at once, a wish to be left alone, or to be allowed simply to exist without being pushed around by whatever comes next.
The strangest detail is the setting: "rooms which are not yet / ready for us." It suggests a future that hasn't been prepared, a kind of waiting room where the speaker and others are held before life properly begins or changes. Judging by that image, the feeling is uneasy but not panicked. There's patience in it, and a little vulnerability.
The mood is hushed and intimate. The short lines and plain words make the speaker seem to be murmuring, jotting down private wishes to a fate that may or may not be reading.