Is there any way (tweak or unregister dll) to remove a button from a program like the button with the red elipse?

1- Right-click on the toolbar.
If you find the "Customize" command, then play with it.
If it allows you to show/hide menus, then customize the
UI to your liking and see if the changes are tracked into
the Registry or an INI file or so.

2- Otherwise, you can use Resource Hacker and
edit the "Menu" resources.

That's what I know is possible. There may be other methods, though.

I have found the menu "Favorites" in Resource, but i don´t know how to remove it, can you help me please?

First make a copy of the EXE you are editing (backup).

While in Resource Editor, delete the item you're highlighting. Then, save and exit.

Run the modified EXE to see the effect.