@Carmendavalos welcome to the community. To log out of your son's account you need to look at the bottom of the screen where you see your scrapbook, quests and a cog wheel. You want to click on the cog wheel or gear and then you will click profile then you will see an option that says log out. Click on that and then you can log on to your own account. Hope this helps.
Hello @Carmendavalos, Hearty Welcome to the Candy Friends section of our friendly King Community
I am sorry to hear about the issue!! Did you check if the setting was set to "keep me signed in" OR "remember me" OR something similar to that!! If that option is there and it might have been with your son's ID and password, un-check that option and try to sign in with your ID!
I am assuming you are playing on a mobile device!! If so, can you delete the Facebook App and Installing it again? Once you Delete the App, clear all the Cache, turn off your device for few minutes (like a reset), then turn it on again and reinstall Facebook App & log-in with your ID. ** Make sure to check the option "keep me signed in" (If that option is available, i.e). I am always logged into my FB account, hence, I do not remember exactly how it is set!!
Please let us know how it went!! If this doesn't work, we will think of another way how to clear this