Is there a command to complete delete all files and folders of personal data of uninstalled programs?
No, since every program creates its own folders… there is no sandbox, like on Android, where you have strict directories. There, on Android, you can delete user data with one button, because it uses sandboxes and profiles. Android “application manager” read the profile and delete the predefined folders. On Manjaro, there is nothing like that. So you have to know which folder contain personal data, normally located here:
No there is not.
Depending on the app - you may have configurations and app data in ~/.config and ~/.local. Cache data is stored in ~/.cache - which can be arbitrarily removed.
So I can simply remove the whole folder of a certain app I deleted and don’t want anything more from it,?
By deteling its folder on :
Do not remove the mentioned folders - locate the app specific folders inside the mentioned folder.
You will also need to use the package manager to remove the application.
Yes, that’s what I wanted to say, for example remove the folder of let’s say lollypop folder as I have downloaded it before, uninstalled it from software manager but now I am using rythmbox.
Talking about the mentioned folders, if I want to perform an old school backup, can I copy them to a pen drive then paste those folders in the future into a new install?
Yes, you can do this. But be aware: if the program version differs than the configs can possible not be valid. That could result in crashes, especially when copying configs for the desktop environment.
You could gain some extra knowledge by familiarizing yourself with this wiki page