Remove sidebar from one page and stretch only that one page

please post a link to that page if you would like to get any suggestions.

to stretch teh center for all pages using this page tempalte, add this to style.css of your theme:

.page-template-blank-php .main { width: 970px; }

for just this ‘test’ page (using the page ID):

.page-id-300 .main { width: 970px; }

as these new styles are more specific than the others, you can add them anywhere to style.css (within the valid syntax of a stylesheet)