Some PSU fans should be able to work in an immersed environment (though it has no practical use to it, as it is wasted power).
Just deactivating / stripping it from the PSU is probably the best solution.
It wouldn't be a problem until the fan stops, but i makes no sense to keep it in there, and you wouldn't want your PSU to drive away like a submarine

Most if not all server PSU has fan checks and wont work if you simply disconnect the fan, hence a fan simulator or other way to disable the fan checks. We have close relationship with our PSU manufacturer, so of course we wouldn't waste time doing this manually for our DataTank production installations, it is done directly by the manufacturer.