If a delegator decides to stop delegating to a validator, he or she can choose to undelegate their tokens from the validator. After undelegation transaction is submitted, the undelegated tokens will be locked until the end of the current epoch. Note that the unlocked tokens can be used for a new delegation transaction only starting from next epoch. This means the same token can only possibly generate rewards for you starting from the epoch after next epoch. The token will be made available on in your wallet after 7 epoch is passed