Is it possible to remove unnecessary letters from android-provided keyboard? I have got letters like ż ŗ ï æ ç ñ etc. on my phone's keyboard (generic android-provided keyboard). But in my language (Slovak), we don't use these. I often make typos when writing, so is it possible to remove them from my layout/edit the layout?

I would like to avoid using 3rd party apps.
I'm using CyanogenMod 10.1 Android 4.2.2 and the generic android-provided keyboard (AOSP ?)

I've made sure the language is set correctly (it is), and tried the different keyboard layouts available for it – but the problem remains.
As you didn't give much details, we can give generic answers only.

It very much depends on the keyboard app used: some allow modifications, others don't. You can either switch to a different keyboard layout (almost all keyboards support this), or use an alternative keyboard app altogether.