A depositor may withdraw funds at any time — the bank cannot refuse to return them. However, the higher interest rate was offered in exchange for a commitment not to withdraw money, so upon early termination, interest is recalculated at a lower rate, usually at the demand deposit level.
The recalculation applies to the entire period, not just the remaining term. Interest already paid is deducted from the amount returned. The result may be close to the initial deposit, even if the funds remained on account for most of the term.
Some agreements provide milder conditions — partial interest retention or favorable calculation after a certain period. This should be checked before opening the deposit, not when the funds are already needed.
A way to reduce risk is to split the amount into several deposits with different terms instead of one large deposit. Then, if unexpected funds are needed, only part is terminated while the rest continues under the original terms.