App downloaded from cousin's Apple ID is greyed out and cannot delete it from iTunes
Update your Apple ID and password on your iPhone, iPad, iPod touch, Mac, and PC.
iPhone, iPad, and iPod touch.


Go to Settings > iTunes &amp; App Store.
If you're signed out, enter your updated Apple ID and password.
If you're signed in with your previous Apple ID, tap your Apple ID,
    then tap Sign Out.
Then enter your updated Apple ID and password.


Mac with OS X Mountain Lion or later, or Windows PC


Go to the Apple Online Store.
Click  , then click View
Account.
In the Account Settings section, click "Update your Apple ID email
address and password."
Enter your updated Apple ID and password.