i cannot remove Grammarly app form my macbook air

Here's a guide for uninstall. If you get a in use box, then go to the activity monitor in your utilities folder and type grammarly in the search box. Then go to the left top and kill the process.https://nektony.com/how-to/uninstall-grammarly-on-mac

If you prefer to stop using Grammarly for Windows or Grammarly for Mac in a specific application or website, you can deactivate it by following these steps. 

If you’d like to uninstall this product offering, follow these instructions: 

Mac

1. Click on the Grammarly button in the menu bar and select Quit. 
2. Go to Finder > Applications.
3. Find Grammarly for Mac on the list and move it to Trash (or Bin).

https://support.grammarly.com/hc/en-us/articles/115000091591-Uninstall-the-Grammarly-browser-extension