Ants nest in compost bin

I'd leave it.
It's all part of the process of getting your waste down to good soil.

To get rid of them would require some sort of chemical. and that would upset the balance in the bin.

I turn my compost monthly, ants move on after being "re-housed" a few times.

Also, I'm sure an expert will comment, but a compo bin if working properly should get to about 50-70 degrees centigrade, surely that's too warm for ants.......which may indicate that the balance in your bin is wrong?
Just supposition, I'm sure we'll find out in a while.

I would leave the ants, I bet they will make your composted soil all nice and fine like when you see ants nest under rocks and so on, that soil is always fine.
Jackie x