Prevent opening PDF file with WPS Office

I have a Gionee mobile on Android 7.1.1. Whenever I open a .pdf file from its inbuilt file explorer, it automatically opens with WPS Office. But when WPS Office is uninstalled, it asks to choose an app to open the PDF. I tried clearing the default of all apps, but it doesn't affect the WPS Office. How to make the file explorer ask to choose a program when I click on a PDF file, possibly without uninstalling WPS Office?