Do I have to tell a university I've been accepted if I'm still applying to other places?

I accepted an offer of admission to one university, but I’m applying to other universities as well. And if I am applying to other universities do I need to mention about my admission status?

Technically, you’re not obligated to disclose your other acceptances when you apply, especially before you’ve made a final decision. It’s not like they have a central database checking who’s accepted where.

But it usually differs country wise too. By the way @ninetails which university have got admission to?