That's in interesting question.

There's no method I'm aware of for eliminating the antibodies. I'm not an immunologist, but I discuss questions like this from time to time with real immunologists and haven't heard of anything like that. I'm not sure why one would even really want to eliminate existing antibodies since their function is to protect us.

Antibodies stick around because the virus sticks around. In fact, as it tries to replicate it re-enforces the antibody generation even if the replication doesn't result in active symptoms.