Want to remove one of two installations of WordPress

I’m new and don’t know what I’m doing, but I ended up installing WP twice. When I use filezilla to look at my folders and documents there is one called
mydomainname.com and one called mydomainname.com.old. I’d like to remove the “old” one. Do I just delete the entire mydomainname.com.old folder using filezilla? Of is there a program on the control panel that will delete it, or what. Actually, I’d like to go back to the beginning by deleting all the changes I’ve made since I started my account here and reinstall manually WP manually so I can learn how to do that and learn more about WP. I don’t want to delete the mydomainname.com folder, do I? Wouldn’t I leave that and just delete it’s contents so that I could reinstall WP to that folder. HELP

You can delete the mydomain.com.old folder from filezilla. You can also go into the mydomainname.com folder and just highlight everything and hit delete. if you know how to use ssh you can rm -rf mydomainname.com/* and it will delete everything in that folder but not the folder itself. its quicker than doing it via ftp but either one gets the job done.