Swizzy release today a nice tool called 3DS Parental Tool which will help you to remove the parental restriction on your 3DS. All you have to do is provide the service code (from you 3DS), the date of the day and press get the code to obtain your master key and remove the restriction. This tool is based on neimods code release today on his github.

3DS Parental Tool

* Requirements *

- Microsoft .net framework 2.0 or later
- a Nintendo 3DS

* What does it do? *
- Itll generate the master key for you to unlock your parental locked Nintendo 3DS

* How do i use it? *
1. Forget your pin for the parental controls of your Nintendo 3DS after youve locked it
2. go to System Settings (you may have to launch it in 2D mode)
3. Go to Parental Controls
4. Click on Forgot Pin
5. Click on I Forgot
6. Write Enquiry Number into the Servicecode box and click OK (NOTE: Make sure the date set in the tool matches the date on the 3DS!)
7. Click on GetCode this will generate your key
8. Press OK on your 3DS and type in the number then press OK again
9. Do whatever it is you needed to do once you had unlocked your 3DS

* Credits *
- Thanks neimod for uploading the original source code: https://github.com/3dshax/ctr/tree/master/parentool