Using this sendTRX function you can send TRX from one walletAddress to another walletAddress:

trx_amountBigDecimalThe amount of TRX you wish to send to the destination address.
sender_wallet_addressStringThe address for the sending account (sender's address).
sender_wallet_passwordStringThe password which you set up already for your wallet.
receiver_wallet_addressStringThe destination wallet address (receiver's address).
TronWalletManager tronWalletManager = TronWalletManager.getInstance();

BigDecimal trxAmount = new BigDecimal("{{trx_amount}}");
String sender = "{{sender_wallet_address}}";
String password = "{{sender_wallet_password}}";
String receiver = "{{receiver_wallet_address}}";
qkcManager.sendTRX(Context context, String sender, String password, String receiver, BigDecimal trxAmount)
                .subscribe(tx -> {

                    Toast.makeText(this, "TX : " + tx, Toast.LENGTH_SHORT).show();

                }, error -> {