Additional information covers how to reinstate your Google Voice account.
Google Voice service is not to be confused withGoogle Assistant(previously known as Google Now).
Google Assistant is a voice assistant similar to Apples Siri or Amazons Alexa.

Google offers instructions for turning off Google Assistant.
There are some things to keep in mind, however.
To permanently delete a Google Voice account, take these actions.

Navigate to the officialGoogle Voice site.
Sign in to your existing account.
Select thethree horizontal linesorMenuoption in the top left.

fire up the menu and choose theSettingsoption.
Disable voicemail support for Google Voice numbers.
SelectVoicemailin the left menu, and uncheck the box next to theGet voicemail via messageoption.

Choose thePhone Numbersoption on the menu.
Select theDeleteoption underneath your listed Google Voice Number.
The system will ask you to confirm your selection.

SelectProceedto delete your number.
Your Google Voice number and account are now disabled.
If you used the web app instead, then you shouldnt need to remove anything.
What Happens to My Google Voice Account?
Afterward, the number will likely go to someone else.
Reclaim your old number by selectingGet your old number back.