Deleted file on MacOS still occupying space
You need to empty your Trash. When you delete a file that just moves it to the trash. To free up space you must empty the trash.
Then you have to suspect that your spotlight process that feeds these displays is stuck. Log out of your account and then restart the mac.
See if you can reveal in finder the app below the one in question.
If the app in question is stuck, rebooting to recovery and then running disk utility to check / repair the filesystem would be prudent. Making a backup also would be prudent if this is a sign of directory damage. You can fix that easily with an erase / install - then load back the apps from backup.