How do you deactivate ctrl button? I mean when you hold ctrl button in gimp and click on the canvas it will turn into color picker and picking color whereever you click, pretty anoying for me because i often use undo button which is ctrl+z. I already looked at the shortcut edit and formating all of the shortcuts, but it seemed it's a default button or something for gimp.
I was searching on internet and can't find a solution, so i found this forum and i though this might be better place for asking. Sorry for bad english, hope you understand, thanks so much before.

Don't know how or even why you would want to. Especially if as you said you use the Control Z option a lot.
Have you tried resetting the defaults at the bottom of the colour picker tool options?

Actually would help too if you gave us a little info - Operating System, Gimp Version.

Ctrl / Shift or Alt are key modifier in GIMP of the selected tool (as well as in many other software).

Now, it would be interesting to know, before to give an answer -> if you hold the Ctrl key and click on the canvas at the same time... what are your expectations?

Ctrl-click as the color picker only happens in paint tools.

You can define shortcuts to start tools/plugins, but once the tools are started their key/mouse usage is hardwired and cannot be changed.

You could envision an external application that filters out Ctrl-click for Gimp, but this specific key-mouse combo is very useful in many other tools (selection tools, brush....) so you better leave it alone.

One solution for you is to go to "Edit > Keyboard shortcuts" and change the shortcut for "edit-undo" to something else that doesn't require the control key.

But, on the whole, in the long run you are much better off learning to keep you fingers off the Ctrl key and learn to use the standard keys.