You can create new text documents.
What you're probably running into is the hidden .txt ending.
When you save in Notepad, under File > Save As, choose the file type "All Files (*.*)" instead of "Text Files (*.txt)", and then it won't add the hidden .txt to the end of your file (leaving your with something like myfile.ini.txt or myfile.cfg.txt etc, except you don't see the .txt as it's hidden).
To disable the hiding of file extensions for known file types in Windows 10 (so you could just rename it even if you forgot to select type All Files), in Windows Explorer, select the View pane up at the top (File / Computer / View), then, click the 'Options' button, then click 'Change folder and search options'
OR (this way is much easier)
Open up Run (Win + R), and type
control.exe folders
and hit Enter
Now you have 'File Explorer Options' open.
Click the View tab, up by 'General - View - Search'
In the 'Advanced Settings' section, find and de-select 'Hide extensions for known file types', click Apply, and you're done. You may also wish to adjust other viewing settings there to your preferences.