How to restore Default Apps by File Type?

[General_Cool]

So I recently screwed up while trying to edit a .ytd file and clicked "always open with" on Notepad. I want to restore it back to the basic Windows thing where it doesn't open with anything if clicked on. I already tried resetting to the Microsoft Recommend Defaults to absolutely no avail. I also tried going to Command Prompt and typing "ASSOC .ytd" and it tells me that it cannot find a file association for it. This concerns me not only because it is incorrect, but because it does not correlate with Settings. Am I screwed or is there a fix I'm missing?

Some screen shots to understand what I'm saying a little better, the second pic is just an example of some GTA V mod files that are screwed up as a result, pics 1 and 3 are to show what Win10 is contradicting:
https://www.dropbox.com/s/ec3t22m72d2aijl/Screenshot%201.png?dl=0
https://www.dropbox.com/s/vx0tm8qpp9oj0zd/Screenshot%202.png?dl=0
https://www.dropbox.com/s/gdakdg57dc75sfm/Screenshot%203.png?dl=0

 

[wpgwpg]

Right-click the YTD file and click "Open with...", then click "More apps". There you can click on whatever you want to have open those files.

 

[gardenman]

I think General_Cool wants to remove the file association, rather than associate the file with another program. There might be an easier way to do this, but it should work for you.

- Download [Default Programs Editor], unzip it and run it.

- Create a backup before you start:
At bottom choose Create or restore a backup of registry settings.
Restart in Admin mode if it asks.
Click on Create a backup.
Choose OK.
If things go wrong, come back to this and restore the backup.

- Delete the File Extension:
Choose File Type Settings.
Choose Delete an extension at the bottom.
Type in .ytd in the search box at top/right.
Click Delete Extension at the bottom.
Program may want to change to Admin mode, allow it if needed.
Click OK.
Click Close.

- Restart Windows Explorer to clear the icon association:
Right click on the taskbar and choose Task Manager.
Under Processes, scroll down and find Windows Explorer.
Right click on it and choose Restart.

It should be fixed.