Press and hold the app icon until it wiggles. Press the little "X" to delete the app. Confirm delete. Press home button to get out of 'wiggle mode'. Sign out of your Apple ID from your friends phone.
Next step- don't sign into YOUR Apple ID on other peoples' phones. WTF...
No, you cant delete it remotely.
You will have to have access to his phone and then delete it manually.
And like said above don't give anyone your apple ID and password.
You did not specify that you wanted to do this remotely, so chill out BRO.
I wasn't going to ask before...but WHY would you sign into your Apple ID on someone else' phone in the first place? It's all YOUR fault, you know. For being careless. Just saying.