What socket is it? Use Cpu-Z to tell us, that is if it still runs
http://www.cpuid.com/softwares/cpu-z/versions-history.html
And does the case have cpu cutout? What kind of heat sink is in the way?
You may have to run the system awhile to make the thermal paste let go. Turn it off after it has ran awhile and take off the side panel.
Touch your power supply with it plugged in and off to ground yourself.
then remove the heat sink, on all cpu sockets I have ran into there is always a retention lever. Undo the retention lever all the way and gently remove the cpu straight out. Do not set the cpu on its pins.
If you have another cpu you are upgrading to, wait until it gets there so you will have a container to store that old cpu in.