I use this button using the command line of USB Safely Remove or Zentimo (Same developer, the functions change, but the command line is the same) Maybe if you only use the command line no license is required.
This is for zentimo:
@set driveletter = {sourcepath$|\}
Go /thispc
"/programfilesx86\Zentimo\usr.exe" STOP -d {$driveletter} > %TEMP%\USRResult.txt
SHOW PLUGIN=text %TEMP%\USRResult.txt
Just go to any folder on the pendrive or select in the folder tree and press the button. Don't work in ThisPC folder
The original post where I got inspiration