In the Harmony network, you have to wait for your funds to unbond after unstaking. But if you want to redelegate them, you can do it using the unbonding sum. In this case, you only need to wait for the end of the current epoch.
How to redelegate:
First, go to the Staking tab and start the unbonding process of the current amount using the Unstake button. Then you have to wait for the end of the epoch (about 1.5 days). After that, you can delegate your funds once again to any validator. More info about how it works in the network can be found here.
Note that if you delegate your funds before the unbonding period has passed (7 epochs), the funds for the new delegation will be taken from your unbonding balance, not from your wallet balance. In this case, your wallet balance will not change because the sum for the delegation were not taken from it, but from the funds that have not yet been returned to your wallet after the undelegate.
Let's pretend that you stake 1000 ONE, and later unstake them, at which point the unbonding process begins and lasts for 7 epochs. If you want just get your staking amount back, you have to wait for it to unbond. But, if you decide to stake 500 ONE before the end of the unbonding period, your wallet balance will not change, and that 500 ONE will be deducted from your unbonding balance. After the end of the unbonding period 500 ONE will be returned to your wallet balance, 500 ONE more will be staked.