How to Delete System Restore Points in Windows?

In the Start menu, click the Search field and type "Create arestore point". 
Click on the "System Restore" tab.
Select your drive (eg C: - protection should show as "On" - and click the Configure button next to "Configure restore settings, manage disk space and delete restore points".
At the bottom of the dialog box that pops up, there is a button for "Delete all restore points for this drive". 
You can then create a new restore point as you wish.