code: public void deleteUserDataPair(String connId, String key) throws WorkspaceApiException {
          try {
              VoicecallsiddeleteuserdatapairData deletePairData =
                      new VoicecallsiddeleteuserdatapairData();
              deletePairData.setKey(key);
              KeyData data = new KeyData();
              data.data(deletePairData);
  
              ApiSuccessResponse response = this.voiceApi.deleteUserDataPair(connId, data);
              throwIfNotOk("deleteUserDataPair", response);
          } catch (ApiException e) {
              throw new WorkspaceApiException("deleteUserDataPair failed.", e);
          }
      }
docs: Delete data with the specified key from the call's user data.
  @param connId The connection ID of the call.
  @param key The key of the data to remove.