To uninstall applications from Emulator:
Way 1: From command prompt:
Step1: Open command prompt.
Step2: Open folder <Your Drive/path>android-sdk-windows-1.0_r1tools
Step3: Type in "adb -e shell rm /data/app/Appfile.apk"
Way 2: From Eclipse
Step1: In the DDMS prospective open File Explorer (Emulator should be running)
Step2: Open "data/app" and you will find all the application you have installed on your emulator.
To Uninstall application from Device:
Step 1: Open Settings -> Applications -> Manage Applications.
Step 2: Scroll to your application, tap on the application,
Step 3: Select uninstall button.
Hope it helps all beginners