Note: For managing apps transferred from HockeyApp please read this article. 

In the App Center dashboard, select the application you want to transfer. When the application opens, select the Settings option in the navigation pane on the left side of the page. 

In the upper-right corner of the App Settings page, to the right of your App Center user name, click the three dots highlighted in the figure below. A pop-up menu will open with the option to transfer the app to an organization.

Note: In order to transfer an app to an organization, you must have admin permissions to the app you wish to move, as well as admin permission to the organization you wish to move it to. 

Next, you’ll be prompted to select the target organization for the transfer. Select the target organization, then click the Transfer app button to complete the transfer.

You can read more about creating and managing apps in the App Center documentation.