Thank you thank you thank you!Don’t worry. You don’t have to drain the reservoir. Just don’t add any new water, and eventually it will come down a little.
If your ambient is 50%, then you should be fine with no water added, or just a little added. Your reservoir will eventually evaporate, and then only add more water if it dips below 50. If dipping below 60 makes you nervous, then add a little bit at 60%.
But with 50% ambient humidity, it might be pretty slow to evaporate, so I think you will be fine.