It’s possible for you to just sign out from your PUBG mobile account and if your account has been created via guest all you have to do is contact the customer support and they will take care of it, but if you used Google to sign up for your account you have to do the following:
1- Go to settings on your mobile and open it.
2- Click on Google.
3- Click on connected apps.
4- Select PUBG mobile and click on disconnect.
5- Also select the option that says “Delete data activities on Google”.
6- Click disconnect.