If you need cash and hold a certificate, you usually have two routes.
Breaking it: many certificates cannot be broken in the first 6 months. After that, the usual penalty is that the bank lowers the rate for the period already held and claws back the difference in the return already paid, so you can get back less than the amount you placed, and the certificate ends. Some certificates allow breaking part of it only.
A loan or overdraft against it: many banks offer this, up to a large share of the certificate's value. The certificate is not broken and runs on under its terms, but it stays held, even after its maturity date, until the loan is fully repaid. The loan itself has its own cost, set in its contract.
The choice between the two is yours, depending on how long you need the money and what each route costs in your case. Check the certificate's key-facts statement: when breaking is first allowed, the penalty table, partial breaking, and the terms for borrowing against it.