Clearing default opening app Whenever i open .pdf file from file explorer it automatically opens with wps office but when wps office is unstalled it ask to choose app to open the pdf..How to make file explorer ask to choose program when i click on pdf file.I tried clearing default of all apps
There are multiple ways to clear the default action app:


you already noticed it gets cleared when the corresponding app is deleted
same applies if you install another app that could perform the same action
there's a menu in settings where you can clear the default without (un)installing an app. Unfortunately, it's hard to find. Before Android 7 it had an own menu entry in settings. Since Android 7, you need to go to Settings › Apps, tap the app's entry, and will find if it's set as default. With that option you can also made it the default, or remove it from being default.