After software removal, software still reads in desktop central as being installed on assets

In our office we've had an issue with Plangrid being auto installed on all the computers and causing issues. So recently we finally worked out how to remove it and stop it from being auto-installed. However, after doing this desktop central still shows all the computers as having Plangrid installed. Doing a scan doesn't change the reading. Reinstalling the agent doesn't change the reading. The only solution I've found so far is to completely remove a computer and then re-add it, only then does Plangrid no longer read as being installed. I'm curious why the system is not accurately refreshing the information on what software is installed on an asset. I'm also curious if there is any less tedious way to get desktop central to accurately read the installed software.