remove xcode recent projects from dock menu

I would like to remove from Mac OS-X taskbar (Dock) the XCode's recent project menu items.
Everywhere I am searching it says the File->Open Recent->Clear Menu it will clear, but not.
It doesn't clear from Dock, it clears from inside the XCode Recent menu.
I believe I should dig somewhere is OS filesystem, but I don't know where.

It was an XCode 4.2 intalled, I did a complete uninstall and installed version 4.3.
But I couldn't clear the Dock's projects menu at version 4.3 either!

Here's what works for me:

1. Launch Xcode
2. Select File->Open Recent->Clear Menu
3. Right-click the Xcode icon and select "Show All Windows". You should now see only your current document in the recents list at the bottom
4. Quit Xcode.
   The recents list should now only be populated with your single current project.

1. Start Xcode
2. In Menu: File -> Open Recent -> Clear Menu
3. Close Xcode
4. Remove Xcode from Dock
5. Reboot

Turned out that all you need to do is:

1. Clear Recent Menu with Xcode
2. killall Dock

Select File->Open Recent->Clear Menu

Remove Xcode from the dock

Re-add Xcode to the dock

Warning: This solution will wipe the passwords of all your developer accounts in Xcode (Xcode > Preferences > Accounts); If you apply this method, you will have to re-enter them afterwards.

---

This is what worked for me in El Capitan / Xcode 7. In Terminal:

% defaults delete com.apple.dt.Xcode
% killall Dock

(Source: https://simon.heimlicher.com/articles/2011/07/26/disable-recent-items)

Strangely, the recommended command:

% defaults delete com.apple.dt.Xcode RecentDocuments

...gives the message:

> Domain (com.apple.dt.Xcode) not found. > Defaults have not been changed.

...so I removed the RecentDocuments part and decided to go nuclear. Haven't checked what else is nuked (other than the passwords mentioned above), so use at your own risk.

1. Open Xcode then choose: File -> Open Recent -> Clear Menu
2. Open Terminal then type: killall Dock