Help! SIRed to UCLA but accepted to USC today

<p>When I was accepted to UCLA like two months ago, I sent SIR right away because I didn't want to wait 'till late June to mid July for USC.</p>

<p>I got my packages from USC today, so I'm in a dilemma where I can choose between UCLA and USC.</p>

<p>My problem is, I already sent SIR to UCLA. If I decide to go to USC after all, do I have to inform UCLA? Or is it just straight up impossible to attend different university after SIR?</p>

<p>Please help me!</p>

<p>If you want to go to USC, you can just call admissions and withdraw your SIR it won’t be a problem.</p>