How to Delete an "Undeletable" File

1. - Open an elevated command prompt

Start > Search "cmd" > Right Click cmd.exe > Run as Administrator

2. - Leave Command prompt open; Open task manager

3. - End process "explorer.exe"

4. - Switch back to command prompt

5A. - FILE - Change to the directory of your file and delete it.

First run this line: cd "PATH OF YOUR FILE"
i.e. cd "%USERPROFILE%"\Downloads"
Now run this line: del filename.extension
i.e. del filename.mkv

5B. - FOLDER - Delete the folder.

Enter Command: RD /S /Q [DRIVE:]\PATH\TO\FOLDER
i.e
RD /S /Q C:\Users\[username]\Downloads\FOLDERNAME

6. - Switch back to task manager

7. - Restart "explorer.exe"