Page Comparison

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1. Go to the Setup page, by clicking on the Setup menu.
2. On your left-side, under the App Setup section, expand the Customize option.
3. Under this option, expand the Opportunities option and then click on Page Layouts.
   <<screenshot>>
   In Group and Professional editions, you need to click on Page Layout. 
4. Now, on the Opportunity Page Layout, click on the Edit link and remove the section you have added for Celoxis Projects.
   Image Added
   Alternatively, in Enterprise or Developer editions, you can delete the layout itself if you had created a separate one. You will have to select a new layout for the replacement.

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1. Go to the Setup page, by clicking on the Setup menu.

2. On your left-side, under the App Setup section, click on Installed Packages.

3. Click on Uninstall link besides the Celoxis app.
   Image Added 
4. On the Uninstalling a Package page, scroll to the bottom and 
   1. Select Do not save a copy of this package's data after uninstall. Click on the Ok button displayed on the message box.
   2. Check the option Yes, I want to uninstall this package and permanently delete all associated components.
      <<screenshot>> 
   3. Click on Uninstall button.
      Image Added
      

The Celoxis app will be deleted from your Salesforce account.