Will factory-reset delete custom downloaded app's folders? I need to know something. For example an app like Telegram that is a custom downloaded app uses two ways of keeping the data,


in the cache folder and since it is stored in /data 


it will be removed

internal storage>Telegram>Telegram Images/audio/...  


will this folders be deleted too?



btw I'm using an Android Tablet, I don't know if it makes any difference.
Yes it would delete.

Although if you have a Google account signed in to the device, and the app is written in a way, the app data may be backed up to your Google Drive and can be restored the next time it is installed (given this feature isn't turned off in settings.)

some older devices/android versions may give you the option not to clear internal storage.