I cannot remove Administrator Rights from any app I gave admin rights to two apps I have on my Motorola Moto G5 Plus (Android 7.0): Find My Device; Greenify Automator. The first one I mean to keep it as admin, but I would like to remove Greenify. When I try to do so, it simply won't let me.
I try selecting "Deactivate this device administrator" but nothing happens. And nothing happens either if I try selecting "Cancel". It seems like these two buttons are just deactivated.
I then also tried doing the same for Find My Device, and it also doesn't work. So I guess it's some kind of bug when removing Device administrators.

Someone know how to solve this?
It was blue light screen filter that was causing the problem and deactivating that fixed the problem as confirmed by OP .Tinted screenshot lead me to suspect this :-)

For additional details on what such apps do see What does &quot;Drawing over other apps&quot; mean?