Function prune_blockchain 

async fn prune_blockchain(
    state: CupratedRpcHandler,
    request: PruneBlockchainRequest,
) -> Result<PruneBlockchainResponse, Error>

https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server.cpp#L3453-L3476