Not sure how to do this without messing it all up, not a pro linux geek… Yet
But, want to be able to install Wordpress or other pages/apps/whatever to the root of my domain, so my installation goes from www.domain. com/blog to www.domain. com but that isn´t possible according to the Yunohost app installer, since something is already there, I assume it´s the admin & user interface.
Is it possible to move that to a subfolder instead or to a different port without destroying the whole system, to like www.domain .com/yunohostadmin or as www.domain .com:port so that Wordpress or other pages opens in the main folder without /folder/index.php
www.domain.tld/yunohostadmin will not work if you want to install WordPress on www.domain.tld because the WordPress need all the paths to that domain Eg. www.domain.tld/somthing would give you page not found by WordPress when WordPress is installed on www.domain.tld.
Further changing the main domain name would also need that you change the DNS accordingly to have proper legitimate mails sending.
So you have two option go with YunoHost main domain change to something like yunohostadmin.domain.tld and change the DNS for settings to have legitimate SMTP.
After you install the WordPress on www.domain.tld, you will need to redirect domain.tld to www.domain.tld otherwise whoever will go to domain.tld will reach to the admin interface of YunoHost.
For this you will have to create a domain with domain.tld, install LetsEncrypt on it and go to /etc/nginx/conf.d/domain.tld.d/ and create a file redirect.conf with this in it: