关于抵押和赎回的方法，拿eosjs举例
https://eosio.github.io/eosjs/guides/2.-Transaction-Examples.html

Stake 抵押

const result = await api.transact({
  actions: [{
    account: 'eosio',
    name: 'delegatebw',
    authorization: [{
      actor: 'useraaaaaaaa',
      permission: 'active',
    }],
    data: {
      from: 'useraaaaaaaa',
      receiver: 'useraaaaaaaa',
      stake_net_quantity: '1.0000 SYS',
      stake_cpu_quantity: '1.0000 SYS',
      transfer: false,
    }
  }]
}, {
  blocksBehind: 3,
  expireSeconds: 30,
});

Unstake 赎回

const result = await api.transact({
  actions: [{
    account: 'eosio',
    name: 'undelegatebw',
    authorization: [{
      actor: 'useraaaaaaaa',
      permission: 'active',
    }],
    data: {
      from: 'useraaaaaaaa',
      receiver: 'useraaaaaaaa',
      unstake_net_quantity: '1.0000 SYS',
      unstake_cpu_quantity: '1.0000 SYS',
      transfer: false,
    }
  }]
}, {
  blocksBehind: 3,
  expireSeconds: 30,
});

操作细节看以上demo即可，下面我们说下抵押时transfer这个参数。
先看合约 (跳转代码)

if ( transfer ) {
    from = receiver;
}

如果设置transfer参数为true,及把来源的账户修改为接收账户。
也就变成了接收账户自己给自己抵押，由来源账户付钱

查看数据

（查看代码）
抵押数据表明为delband
(查看代码)

del_bandwidth_table     del_tbl( _self, from.value );

是以来源账户为查询的scope
所以RPC查询如下
post: https://api.eoslaomao.com/v1/chain/get_table_rows
data:

{
    "scope": "bcskillsurou",
    "code": "eosio",
    "table": "delband",
    "json": true
}

返回

{
    "rows": [
        {
            "from": "bcskillsurou",
            "to": "bcskillsurou",
            "net_weight": "0.0046 EOS",
            "cpu_weight": "0.0147 EOS"
        }
    ],
    "more": false
}