No you don’t need to delete your whole Google account in order to delete your Google Adwords account.
You can do that in the Settings while you’re logged in to Adwords. We will show you below how we deleted our profile on a desktop computer:
1 Sign in to your Google Adwords account
2 Choose Account Settings
after selecting the gear wheel in the upper right corner.
3 Cancel this account
is a link that you’ll find on the bottom of the Account Settings page.
4 Cancel my account
is now the final button to deactivate and close your Adwords account.
Your account has been successfully deleted. You will receive a final bill from Google within 60 days.
Source screenshots (& thanks to): adwords.google.com