If I uninstall an application from one administrator account in Windows 7, does it delete it for everybody?

On one of the laptops I use, there are two administrator accounts. I created one for myself and one for a friend of mine.

If I were to uninstall a program, would that also uninstall the program on my friend's account?

When you uninstall any program from your hard disk. It will uninstall both accounts because you have only one hard disk in your computer and 1 Windows (Operating System).

if you want to access only one account you can change the permission of your program or when you install it some application asking for all user or any specific user then you can decide it that time.

I hope It will help you.

Mostly Yes, But the preferences of each user is specific to his account. That is, the software personalize to each user of the computer. But if you uninstall the software the software, in most cases, will be removed for all the users.

If the software is annoying you, I am not sure how. I can assure you there are ways to keep it quiet for you.

Yes it will remove the program for all accounts.