The speaker wants to be rid of their own imagination, and the reason is a little surprising. The fantasy they describe sounds exciting: two people setting the whole world alight with nothing but a few cigarettes. But the speaker doesn't welcome it. The opening line, "I wish I could do away," suggests the daydream hurts more than it delights.
That's probably because it is only a fantasy. The poem doesn't say why, but the wish to escape it hints at longing for something that isn't real, or isn't possible anymore. The word "we" points to another person, and the poem ends on "And that night," a fragment that trails off without a verb. It reads like a memory or a daydream the speaker can't finish, or can't stop returning to.
The mood is wistful and restless. The language is plain and the lines are short, yet the image of a small, ordinary act lighting up the world gives the poem a quiet, aching intensity.