How did you setup the dual boot??and by linux you mean ubuntu or which flavor of linux is installed??Is windows bootloader in control or grub is in control when you boot up your system??
Post a screenshot of your disk management using the snipping tool by following this tutorial Screenshots and Files - Upload and Post in Seven Forums
If windows bootloader is in control then its easy to delete linux from your system.Just back up all your data from your linux partition.Open disk management from typing disk management in start-search box.Right click on your linux partition and click on delete volume.
Next type msconfig in search box and click on Boot tab.Delete the linux OS entry there and restart your system.
If in case grub is in control and after deleting linux partition within windows 7 you can't boot into windows 7 then follow this startup repair tutorial.Startup Repair
Let us know how it goes