The title is a reference to the opening lyrics of Kurt’s “Radio Friendly Unit Shifter” (which was a music industry term to describe singles that sold a lot of product, be they vinyl, CD or cassette, hence “units”). The lyrics are “Use just once and destroy”. With this explicit reference to Kurt, it’s possible that the song is about her failed efforts to help Cobain, via lines like “I went down to rescue you/I went all the way down/fill your hungry wretched life”. Of course, such an interpretation won’t jibe with those who hold her responsible for his death, which she also alludes to with “All dressed in red, always the bride/off with her head, all dressed in white”, which is comparing how she is seen by those people “dressed in red” i.e., with his blood on her hands, vs how she sees herself “dressed in white” i.e., innocent yet being mistakenly held accountable i.e., “off with her head”

Also, “Use Once And Destroy” is also a phrase found in the packaging of hypodermic needles sold for managing diabetes (and for using heroin)