Can I switch between Unity free and Pro during the trial?

I’m currently using the Pro trial but I wanted to make a build without the “Trial version” watermark for a video – I’m not using any Pro features that would be deactivated, I only wanted the trial to try out the profiler. Anyway, it looks like I can switch back to Free under “Manage License”, but does that terminate the trial or would I be able to go back to Pro until the 30 days are up?

You can go back to Pro at a later date.

Yes it is possible.

What you have to do is quit Unity, locate the license file and make a copy (This will be the Pro Trail version). Open Unity and activate Free and it will override with a free license in the same folder.

You should make a copy of that free license so you have two (Pro Trail & Free) which you should be able to swap between.