You may want to re-post this in an area other than "Polls" so a gardening professional can assist you. Good luck with saving your tree!

I think it's already posted in Palms topic... I'm new here, sorry

It's not a palm, it's a Dracaena which isn't related to palms at all. The good thing about Dracaenas is they're quite tough plants and if abused can still recover quite well when given good conditions again. The problem seems to be root rot. That can happen from either too much water or too little. If the potting soil doesn't drain well the retained water causes the roots to rot. If the soil dries too much the roots wither and die. A bit of wetting later on just makes them rot. Ants in the pot can make the soil dry too fast through aeration, but they can also bring in pests which feed on the roots of the plant and damage them.

First up you need to check the drainage of the pot and whether the soil drains well. You can get rid of the ants by soaking the whole pot in water, they will come up to the surface and you can wash them away.

@tropicbreezent

Thank you very much for your comment. I did as you said. The drainage of the pot seems to be okay, I watered it quite well the other day. Excess of water comes out easily. No sign of ants anymore.

However, what if the problem is that the tree has already had too much water and the roots began to rot? Should I let the soil dry and not water it frequently? Thanks