how to delete old account and credit card info by How do you delete some one else's account off your Android phones play store there is no credit card on it but it makes me have to go and find me and then I can see my info if not it goes to the lady I bought my phone from
Settings > Accounts > Google then select the account which you wish to remove. 

Settings > Accounts > Google >  select the account which you wish to remove > More  > Remove account. 

PS: You'll need to stop Syncing first.

On older versions (1.5 > 2.3.5) there is no way to remove an account, only by resetting the device to the factory settings.