I have seen similar topic but no one them was helpful to me…
I just wanna turn off some unnecessary apps manually.
unable to know what you want to do. Do you want to delete the app icon in launch menu? If so, just Double click the launch icon and edit
Well I have installed app, name “pentablet”, Which helping me only moment when I’m using tablet…
But most of time I’m not using tablet so it’s unnecessary to me, but application style starting when I’m entering in system (booting, Idk which one is correct form to say) cuz of that I want turn off this from automatic startup applications… Sorry for my bad English, I hope you understand what I’m trying to say.
Do you mean the app “pentablet” autostart when os start? If so, you can turn it off in System Setting - Starup and Shutdown - AutoStart. (Chinese is well for me.)
At first I thought that, but its not here… maybe reason is I have installed this app without pacman (Is it? Idk)
Ugh I forget mention it’s more like driver for this tablet with graphical UI…
driver… Far beyond my ability. 
unable to help
There is no such app in our repository, so you either share the exact name or the source from where you installed it. If you are talking about the AUR (en) - opentabletdriver then is all documented on GitHub - OpenTabletDriver/OpenTabletDriver: Open source, cross-platform, user-mode tablet driver