CoherentUI_Host.exe is making it so I cannot launch any game via steam, and won't disappear.

As the title says, CoherentUI_Host.exe is constantly on my task manager, meaning steam thinks the entire game is still open, meaning that I cannot open another. You might say "Just end the task", to which I say that when I try, it tells me that "This operation cannot be completed, this access is denied."
Even after restarting my PC numerous times, the CoherentUI_Host.ext will not leave. I have found no way of stopping this. Any help?
I'm on windows 10.

So apparently Windows has been doing this since Windows 8 came out. I guess it carried over to 10. Even with Administrator right, it will prevent you from killing certain tasks. It seems it can occur when processes get hung on I/O operations. So there are a couple of things you can try (source):
Thoroughly check all of your hard disks for errors.

1. Right click the start button
2. Choose "Command Prompt (Admin)"
3. If you're prompted by UAC, enter your password, or click Yes to continue
4. type "chkdsk c: /r" without the quotes, and press the enter key. Replace C: with the disk that Windows 10/8/8.1 is installed on.
5. When prompted to check the disk on next restart, type "Y" without the quotes, and press enter.
6. Restart your computer.

If you have any programs/games installed on a drive other than your Windows system drive, you will want to check that drive the same way after reboot. It is also a good measure to check any drive attached to the system this way about once a month or so.

Check your system for corrupted core system files

1. Right click the start button
2. Choose "Command Prompt (Admin)"
3. If you're prompted by UAC, enter your password, or click Yes to continue
4. Type "sfc /scannow" without the quotes, and press the enter key
5. Once the process is completed, restart your computer.