revoke_calendar_access.rb

# client => Any Google API client
# refresh_token as token in params is mandatory.
uri = URI('https://accounts.google.com/o/oauth2/revoke')
params = { token: client.refresh_token }
uri.query = URI.encode_www_form(params)
response = Net::HTTP.get(uri)
# will get a {} if access is revoked and errors if any.
result = JSON.parse(response)