Running application in flash is correct way

As even though i clear all GDI objects using Deleteobject and Delete DC, still my application is getting memory leaks how to solve it

There may be many reasons of memory leak other than GDI objects.
It’s application specific and one can use “remote resource leak detector” tool available for WEC7 for memory leak detection and debugging.
This is one of the tools available in platform builder (Windows Embedded Compact 7).
Please go through the link for your reference.

Also there are many third party tools available to detect memory leaks in your application like

On what platform are you running your application?
If you can provide us more information about module you are using, image version and a small application that can reproduce the issue we will try to investigate it on our side.