I am learning meteor and have created a new app and installed accounts-core, accounts-google and accounts-ui. This worked as expected and prompted me to configure the google in
If you need to do this on your production server, where you don't have meteor but you can run mongo from the shell, then the process is pretty similar:
$ mongo
...
Welcome to the MongoDB shell.
...
> show dbs
foo 0.078GB
bar 0.078GB
my_meteor_db 0.078GB
> use my_meteor_db
switched to my_meteor_db
> show collections
...
> db.meteor_accounts_loginServiceConfiguration.find()
...
> db.meteor_accounts_loginServiceConfiguration.remove({service:"google"})
WriteResult({ "nRemoved" : 1 })
> exit
bye
$