RTF is a global modification that replaces all towns in the game.

Question: where can I change it?

The easiest way is through the advanced map editor (you can change almost anything through it), but you need to figure out the special panel.

Added 8 minutes later

Question: where can I change it?

http://psatkha.narod.ru/tutorial_ru.html
From this tutorial, you need to complete steps 1 and 6, but you need to select TownBuildDefinition, then choose the building plan for the desired faction in the window, and the building plan will appear in the map properties window, where you can change everything.