Just killing the com.apple.dock.plist from the finder may not work because the system holds the current settings in memory and will just write them back.

You could try and delete it from Terminal.app

In terminal type

defaults delete com.apple.dock.plist;killlall Dock

Just killing the com.apple.dock.plist from the finder may not work because the system holds the current settings in memory and will just write them back.

You could try and delete it from Terminal.app

Update.

Go to ~/Library/Application Support folder in Finder and remove the folder:

Dock (this holds a dock database )

Then in terminal type and run

defaults delete com.apple.dock.plist;killall Dock