Bail is revoked by a judge usually on a request from either an assistant district attorney of from the county's bail agency or pretrial services. Both examples are almost certainly going to lead to at least a modification (increase) in bail. I'd love to hear some elaboration on the comment the questioner posted concerning what appears to be a direct communication from the DA threatening revocation of bail unless a guilty plea was tendered. Are you unrepresented? If so, you need counsel immediately. If you can't afford privately retained representation, apply with the Public Defender.