Yes. There is no obligation to deposit upon registering to 24option. Only when you actually want to start trading will you need to make the minimum deposit of $250.
Trading in Binary Options, Forex/CFD carry a high level of risk to your capital due to the volatility of the underlying market. These products may not be suitable for all investors. Therefore, you should ensure that you understand the risks and seek advice from an independent and suitably licensed financial advisor.