trying to install adobe flash player on windows 7
I have never had to disable avast to install or update adobe flash player.
Why is it that you believe (or are told) you need to do this ?
It is easy to temporarily disable avast, right click on the avast tray icon > Avast shields control > disable for X duration. That said, it should be the exception rather than the rule to disable your protection at the very time when it is most necessary, installing programs/apps.