You can unstake your eGold at any time.
The entire unstake process takes 10 days:
you first have to initiate the unstake process, through an unstake transaction.
(Earn ->Staking -> Unstake)
and 10 days later, you will need to finalize the withdrawal of your unstaked eGold. (Earn -> Staking -> Withdraw)
Only after those 10 days have passed and only after you have successfully withdrawn your unstaked eGold, they will be available in your wallet.
*During those 10 days, your eGold will not be eligibile for any rewards.