The term is usually used negatively, to suggest that someone outside the group is actively doing things that hurt or diminish the group's standing. Sometimes the group does things that might reduce its own visibility, however, that is usually not describes as "erasure".
The opposite of erasure is visibility. Often, members of a minority are forced to reduce their own visibility in order to protect themselves — this is called passing. Also, some stigmas are inherently less visible while others are inherently more visible, and this affects the decisions a stigmatized person can make when interacting with acquaintances.
Groups who are often concerned with erasure include: