Yes, your AdWords account is completely safe. During the integration process we do not ask for your AdWords account password - and we never will. We are simply asking for Google OAuth access which is something that allows us to view your ads data so we can analyze and determine their legitimacy.
To read more about OAuth access, check out this article:
Why do you need access to my Adwords account?
Note: When approving access to PPC Protect you notice that we require “Full access to your AdWords account”. This is because AdWords only allows us to choose one of two options when accessing accounts through the API - “Full Access” or “No Access”. The only thing PPC Protect will change in your account is adding or removing fraudulent IPs from your IP blocklist.