windows 10 - Can't delete a file even though I'm on an administrator account, and I have full ownership of the file?

Downloaded an installer. Ran it. Didnt like the program so I uninstalled it. However, the installer file is still on my desktop.

Windows 10 64 bit.

I'm on an administrator account.

I right clicked on the file and went to properties and then security and looked at the ownership. I have full control.

Found a link on superuser and it said try doing takeown from the cmd. I tried that. All it said was access denied even though I ran cmd as an administrator.

Found another post on here that said run explorer as an administrator. Tried that. Still getting access denied.

I know if I reboot my PC I'll stop getting the message and I'll be able to delete the file. I just want to know why I need to restart my machine to unlock the file. There has to be a way to do it without restarting my pc or downloading an unlocking program.