Of course you can remove the moss.
You could also use a chopstick or something similar to poke carefully into the pot. When you retreat it from the pot the humidity of the soil is 'displayed' on the stick. Depending on how easily it slides in you can feel how dry it is.

Can't resist to say how beautiful that tree is though! What are your plans on it?

You can remove the moss if you wish, it is fine, but you could also grow the moss you have collected.

Thank you bob and Contrainer! I think I will remove the moss then. And try to grow it separately. That will be a whole new project on its own.

It's beautiful isn't it? I think it's a very young plant but it already possesses some good tree-like shapes. I like it a lot and am wary of a wrong move. I might let it grow unrestrained for now and see what happens? Any other idea? (I'm a very beginner).

When you shred the moss in small pieces, mix it with dry coffee and sour milk/coffee milk it grows rapidly like never seen before.
Smear it on a rock/tile in a not too thick layer for nice results.

I'm not very pro either so I can't give you much ideas concerning the developement of your tree, but I'd let it grow unrestrained now, yes.

Enjoy your bonsai!

Letting this plant grow unrestrained will mean you have lost all ramnification by the end of the year.

Advice on what to do depends fully on what you want to achieve

Thank you guys. I guess it's time for me to do some reading, and then decision making!

SORRY to put up a thread so old, but...
This is not a very common bonsai around here. People say it is huge in Vietnam, and the fruits are small and edible.
The thing is, I am delighted!
I've just got a Dwarf Kinzu Orange (Hong Kong Kumquat - fortunella hindsii) as a gift, from a very good friend (a client in fact), and it is beautiful.
The previous owner says it fruits regularly, and now (as today), it is full of young shoots.
I'll post a picture below of a fruiting one (from the internet), and mine as is today:

From the Internet:


My Kinku, now:



I am sure I'll have a LOT of fun styling it in the near future!