Should I close my Saxo account and go for robo advisor, if I am not good in investing?

It is up to you.

If you opt for a roboadvisor, you just need to choose how much risk you're willing to take, i.e. how many % in bonds, how many % in stocks etc, and the diversification wlll be done for you.

So far it seems you've only invested in Singapore. You can consider investing in a roboadvisor like Autowealth (since you have 3k) for global exposure. Or you can also DIY and purchase a broad-based ETF like VTI or it's Ireland-domiciled counterpart. If these terms sound foreign to you, then perhaps stick with a roboadvisor first, and read about how to DIY in the future.

Hope this helps!