async delete(config, netEngine, sessions) {
    const SessionDeleter = shaka.offline.SessionDeleter;

    let deleted = [];
    for (const bucket of SessionDeleter.createBuckets_(sessions)) {
      // Run these sequentially to avoid creating multiple CDM instances at one
      // time.  Some embedded platforms may not support multiples.
      const p = this.doDelete_(config, netEngine, bucket);
      const cur = await p;  // eslint-disable-line no-await-in-loop
      deleted = deleted.concat(cur);
    }
    return deleted;
  }
Deletes the given sessions.  This never fails and instead logs the error.

@param {shaka.extern.DrmConfiguration} config
@param {!shaka.net.NetworkingEngine} netEngine
@param {!Array<shaka.extern.EmeSessionDB>} sessions
@return {!Promise<!Array<string>>} The session IDs that were deleted.