Keywords: aloof, quit, withdraw, resign, drop out, pull out
As a Verb or Adjective
To stop doing something, especially being a member or participant in some organisation or activity. English = quit, withdraw, resign. Idiomatic English = drop out, pull out.
To not become involved in something. English = stay aloof, keep aloof, remain aloof.
To like to be alone and not talk much to other people. English = (be) aloof.