You might want to delete app cache and app data on your Android phone in many a situation. When an app stops working or will not open up, when it misbehaves or do not work as it is supposed to are the common reasons. Deleting app cache and app data on Android 6.0 Marshmallow are slightly different than we did it on the previous Android versions.
This tutorial explains how to clear app cache and app data on Android 6.0 Marshmallow. You can delete app cache and app data on Android 6.0 by going to Settings -> Apps -> Storage and selecting respective options. Depending on the situation of the issue, select app cache or app data.
For example, if an application takes long time to open up or slow down its performance, delete app cache (Settings -> Apps -> Storage -> Clear Cache). Cached data will not take up a lot of your memory, but it can drastically slow down performance if you let it build up too far.
Now, if an app will not open up or stop responding, then delete app data (Settings -> Apps -> Storage -> Clear Data). However, please note that this removes all your personal settings, accounts, and files associated with the app. That is, it reverts to the original installation of the app.