otTcpCircularSendBufferForceDiscardAll() function
Forcibly discards all data in the circular send buffer. The application is expected to call this function when a TCP connection is terminated unceremoniously (e.g., if the application calls otTcpEndpointAbort() or is informed of a reset connection via the otTcpConnectionLost() callback). Calling this function on a nonempty TCP circular send buffer attached to a TCP endpoint results in undefined behavior.
Arguments
aSendBuffer
The TCP circular send buffer whose data to discard.