could you please tell me where can i find the folder where games of game pass are installed...

Game Pass for PC games are installed in "<drive>:\Program Files\WindowsApp" folder. It's a protected folder, so you might not initially have access to it without additional configuration or settings changes.

BUT

Since you're looking to install the App that doesn't appear on your start menu, I would first look at Settings > Apps and see if the App is in that list. It will provide options to uninstall the title, reset it, or other options that might help with your
issue. You should also be able to install the title from the Xbox (Beta) App itself, as well, by right clicking on it and selecting "Uninstall"

Let me know if they don't show up in those places, either, and we can see if there are some other steps to try.

You could also try to look in the Microsoft Store app in the area for Game Pass and other subscriptions.

You also can choose the directory you want to install the game, just change the letter if you have another partition or hdd, from C to D, in that way will be more easy to find the game directory. By the way the games can´t be erased, you must unisntall it,
because erasing the game will left other folders in other locations, so the proper way is uninstalling from control panel...

Can you please tell me where I allow mobile installation cause I can’t find it

Do you know the folder where the game was installed?

Can you check if there are still files in there? Maybe you can also find the game's uninstaller and try to uninstall it again.