How Do I Remove Project Name From My Combobox

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XAML

WPF

Hi Everyone,

I have a combo box which i have bind the items reading from the database. now i have added the style to the combo box by doing the following;
(right click combo box ->Edit Template -> Edit Copy and i have applied to the combo box.)

this was my default text in my combo box
my default text on the combo box was (--Please Select Company Name--)

After that my default text doesn't appear anymore and it is showing the name of the project inside the combo box and my name of the project is this one;
<page windowtitle="Registrations" x:class="UserInfor_Enrollment.Registrations" xmlns:x="#unknown">

Please help on how can i solve this. I tried to remove it and i got this error below
Error 1 'Page' root element requires a x:Class attribute to support event handlers in the XAML file. Either remove the event handler for the Unloaded event, or add a x:Class attribute to the root element. Line 9

Thanks.