How uninstall CC but leave LR and PS

If you are looking to speed things along a little, you could try the following…

Turn off…
Photoshop Preferences > General > Auto show the Home Screen

Turn on…
Photoshop Preferences > General > Use Legacy "New Document" Interface

Yes the cc app runs in the background even if you want to block it... If you do remove the cloud sync then try to run Photoshop/ Lightroom it will automatically fire up a second version of cloud sync which you have to restart your system to remove with out using registry hacks

Yes it is in fact possible to remove the cc app but I don't recommend

You can uninstall the Creative Cloud desktop app, but it is only a front-end dashboard to the background processes that get installed with Photoshop and Lightroom. To really kill those processes you have to do it manually. The challenge for you is that Creative Cloud processes are tightly integrated with Adobe applications, so manually ripping them out could cause some things to not work, or a series of errors, because the applications are built to assume those processes are going to be there. In addition, you would have to rip out those processes again every time you update the software, because every update will probably reinstall them. I haven’t seen an exact list of what all those processes do, but they certainly include:

• Components for lots of things on the Home screen (such as tutorial thumbnails and links). 
• Cloud Documents synchronization. 
• Adobe Fonts synchronization. 
• Creative Cloud Library synchronization. 
• Crash reporting. 
• Licensing verification. 

On my laptop these processes don’t use much real RAM or CPU power (right now it looks like a fraction of 1% CPU total). And keep in mind that the same thing still exists on any Mac or Windows computer with no third party applications installed: If you check your process monitor, there is still a long list of background processes run by the OS itself, that do things like monitor for notifications, verify licensing, check for updates, check feeds, sync cloud services, etc. And those can’t be turned off either. We only have to hope they are all coded well enough not to use up too much power or battery life.

But what is the actual problem that you need to solve?

You have a point. If you only need to check in every 30 days to validate you have a licence so really nothing else should be running outside of your apps. I can't stand things running that I didnt open. I certainly turn off data collection and usage and all that usual baggage... and I will be looking at what else I may be able to turn off in the background.

Adding to what @D Fosse said, you will get this message if you even try to sign out of Creative Cloud.

~ Jane

Why? What harm does it do?

In any case, you can't. The CC app manages your license and updates.