To remove the Web part from the gallery execute the following operations:
Type <portal address>/_catalogs/wp/Forms/AllItems.aspx in the address bar of the browser. It will open the Web Parts Collection page.
Click the button opposite to the web part which should be removed. The dialog box for editing the web part opens.
Click the Delete Element button on the Edit ribbon tab.
See also:
Adding the Web Part of Prognoz Platform 9 to the Microsoft SharePoint Web Page