Steps to reproduce:
1) Open Unity Hub and create a new project
2) Open Player Settings >> Other Settings and disable Auto Graphics API
3) Select one of the Graphics APIs and try to remove it from the list
Note: Add any Graphics API to the list if there is only 1 once the Auto Graphics API checkbox was disabled)
Check attached repro video

Expected result: Selected Graphics API should be removed
Actual result: Selected Graphics API is not removed

Reproduced with:
2020.1.0a24

Not reproduced with:
2019.3.2f1, 2020.1.0a22, 2020.1.0a23

Regression since:
2020.1.0a24

Note: Windows and MacOS