I'm Lucy and I live it texas
 

Should take this wild tree frog out of my corn snakes terrarium?

Yes, and then remove the snake temporarily, disinfect the viv and all the hardscape, discard and replace the substrate. Then either put together an appropriate enclosure for the frog or humanely euthanize it; do not release it.

Mixing any species is a bad idea, but if one of them is WC it is a worse idea.

How long have they been coexisting in same terrarium?

@john Miller why not release it?
@christopher Shelly less than 24 hours.

Yes releasing is a way better option in my opinion especially if the frog is endemic to that area.
I don't think the corn will eat it, also in my opinion I would let thm coexist. To each his own.
Good luck in whichever u choose.

@chrisis so you would keep the frog in there with the snake?
Cause I kinda want to.

If it makes u happy to see it thn do what makes u happy. Everybody can give u there opinion & reasoning but at the end of the day what is important is how U feel. They r ur animals so do as u seem fit!

Releasing it risks introducing novel pathogens to the local environment that it may have picked up in captivity. The life of one frog is not worth that risk, especially given the terrible state of affairs wild amphibians are currently in.

I personally don't think keepers should do whatever they want with their animals, especially when those choices impact wild populations (which, as a legal matter, belong to us collectively).

Rereleasing of WC native wildlife is also restricted or prohibited in some areas/states because of this risk (among other reasons). This isn't to say that this is the case where you live, it is to say that some natural resources agencies have recognized these risks.

What is important is taking the time to do research if one is keeping critters, and keep them in the best possible environment and look out for their health and safety.