Go to the network preferences, select "Wi-Fi", and click "Advanced..." (you may have to click the lock in the bottom left first). Then, in the "Preferred Networks" list, delete any that you don't want.
The passwords are saved separately, in the keychain. I have verified that removing an SSID from the list in the network preferences doesn't remove it from the keychain, so you can delete them without worrying. (this is unlike the case with iOS, where forgetting a network also forgets the password)
You may also want to uncheck "Remember networks this computer has joined" to prevent them from being re-added when you join them again. Again, this is separate from the "Save password in keychain" that saves the password in the keychain when you enter it.
You did eventing right except for one step.
Making new account.
Quit Google Chrome completely.
Go to the Go menu > Go to Folder.
Enter the following directories in the text field, then press Go.
~/Library/Application Support/Google/Chrome/
Locate the folder called "Default" in the directory window that opens and rename it as "Backup default."
Try opening Google Chrome again. A new "Default" folder is automatically created as you start using the browser.
Alternatively you can "teach" your browser.
That is done by adding the :80 to the web address.
Example www.myseite.com:80
Also run the netstat -a -p tcp to see if https (443) are open)
Last not least, turn off the experimental "Built-in Asynchronous DNS" is Disabled in chrome://flags/
Best Answer
If you're running low on memory, you may try to use Safari instead, it allows you to enable single process mode.
For that you need to enable the Debug menu in Safari.
Open Terminal and type in the following command and hit return
Open the Safari app. (If you had Safari opened, you need to quit and open it again.)
You will see a Debug menu, just check the Disable Per-Tab Web Processes item.
It will ask to quit Safari, click the button and open Safari again.
(It will close all tabs, so make sure you don't have anything pending)
Open the Safari app again. You're in single process mode! You can check it by opening Activity Monitor app.
Results
This is not very scientific, but just to give you some idea.
Before (multi-process)
After (single-process)
Reduction in 1.14GB
Reverting
Debug > Disable Per-Tab Web Processesto go back to the multi process mode.