If you see white remains, sometimes this is a Pseudo-nit.
Pseudo-nits may be mistaken for nits (eggs). On closer examination they may be dandruff, hair spray residue, or skin cells. These are easily removed whereas real nits are securely stuck to the hair shaft. The exception is the pseudo-nit known as a DEC (desquamated epithelial cells) plug, which encircles the hair, and is sometimes hard to remove.
DEC plugs (desquamated epithelial cells) may occur when oil glands in the scalp work to compensate for the drying effects of chemical treatments. They are bright, white, irregularly shaped clumps of fat cells stuck to the hair.
Without being there I cannot tell if it is a live nit. Here are a few ways to tell. If the lice or nit are close to the scalp, then chances are it is live. If it is further away from the scalp then it is dead. If the remaining lice or nits comb out easily or fall out then they are dead. They may still be in the head, but they are not alive and are not a threat. Again, they might be stuck because of the hardening of the glue from other products.
Head Lice Treatment