I have invested some money in DBS digiPortfolio, syfe and stashaway and there are some profits. I would like to know if I withdraw these earnings out, will it affect my current portfolio? What's the impact I'm looking at?

A few friends here have already explained the impact of withdrawal

I'd just like to add one word: do not withdraw any earnings or even your capital, instead just Dollar Cost Average (DCA) every month.

Robo advisor is for long term investment, not something that you withdraw the moment you see some profit

It would depend on your investment duration. If you are planning to invest for the long run, withdrawing a significant amount of money out now would have quite a significant impact on your returns at the end.

Simple calculation to illustrate the example.

1000*(1.08)^40 would be $21,700
If 800 would be $17,379
If 400 would be $8,689

By removing just $200, you would decrease the amount that compounding effect can magnify by $4000.