I'm running SCCM2012 R2 SP2 in my lab. I'm looking for the option "Client Setting" so I can look at the Resultant SCCM Client Policy. I go to Assets and Compliance\Devices and highlight one of the SCCM clients, and right click, but the "client settings" option is not there at all. I'm logged on to the SCCM server itself with an account that has Full Administrator access. I can see this option if I select the users category under "Assets and Compliance\Users" but not under Assets and Compliance\Devices. What am I doing wrong ?

There is no such thing as 2012 R2 SP2. Are you running R2 SP1 or SP2? I think the feature you are looking for is in R2 only so it makes sense you would not see it if not running R2. Note that R2 is not free and you are not entitled to it unless you purchased 2012 with R2 or have software assurance.

My mistake. I am running SCCM 2012R2 SP1.

The only reason I can think of for this option not to show then is you do not have the proper permissions to see it. Have you tried to simply restart the console?