When I downloaded an app on my iPhone, it didn't let me delete it, what do I do?

I tried deleting it when it was installing but then it stopped and it just froze

Do a hard reset on the iphone. Which is where you hold down the power button and slide to turn the iphone off. Press the power button again to turn the iphone back on. Then, hold your finger on the app until it wiggles. Tap the "x" on the app to delete it from the iphone.