Uninstalling Linux from dual boot system without formatting

I have a Dell Inspiron 15R laptop. It has 4GB RAM, 500GB Hard Disk space and it is running an i5 processor. I have installed two OS into it. It is running with Windows 7 and Linux. My problem now is, I want to remove the Linux OS without reformatting my device. How can I do that? Please send some help. Thanks.
