It means is where something is removed or erased completely or something unwanted or unpleasant.
Hope this helps and the right meaning of expunge.
Answer: Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association with one of the ...
