aeron-archive/src/main/java/io/aeron/archive/client/AeronArchive.java
public void truncateRecording(final long recordingId, final long position)
    {
        lock.lock();
        try
        {
            ensureOpen();

            final long correlationId = aeron.nextCorrelationId();

            if (!archiveProxy.truncateRecording(recordingId, position, correlationId, controlSessionId))
            {
                throw new ArchiveException("failed to send truncate recording request");
            }

            pollForResponse(correlationId);
        }
        finally
        {
            lock.unlock();
        }
    }
public void truncateRecording(final long recordingId, final long position)
    {
        lock.lock();
        try
        {
            ensureOpen();

            final long correlationId = aeron.nextCorrelationId();

            if (!archiveProxy.truncateRecording(recordingId, position, correlationId, controlSessionId))
            {
                throw new ArchiveException("failed to send truncate recording request");
            }

            pollForResponse(correlationId);
        }
        finally
        {
            lock.unlock();
        }
    }
Truncate a stopped recording to a given position that is less than the stopped position. The provided position
must be on a fragment boundary. Truncating a recording to the start position effectively deletes the recording.

@param recordingId of the stopped recording to be truncated.
@param position    to which the recording will be truncated.