The only way to remove a Gmail account from your Android device is to remove its Google Account. You can prevent Gmail from syncing new emails. However, if you want to remove a specific Google Account from your phone or tablet, follow these steps.
Removing your Google Account means services like Google Maps, Google Play Store, and other apps will no longer be available. You'll need to add another Google Account to your Android device or sign up for a second Google Account to ensure uninterrupted access to these apps.
As mentioned earlier, you can disable Gmail syncing instead. This will prevent Gmail from updating your inbox on your device and will keep your account available for other purposes.
If you want to remove your Gmail account, you must have your device handy, even though you can sign off remotely if necessary from your account.
Disabling Gmail syncing
Before we begin, it's important to note that the steps for accessing your device's Settings menu may vary slightly depending on the version of Android you're using. The following steps should work from Android 9 Pie.
Access your device's Settings menu by either clicking the app in the app tray or by flicking down the notification shadow and tapping the gear icon.
In your device settings, look for "Accounts" or "Accounts and Backup" and click it, depending on what the name is on your device.
Note: On some devices, you need to tap an additional "Accounts" menu to find and manage your various accounts.
Find your Google Account and tap to access your individual account settings. Click Sync Account or Sync Account.
button Find the Gmail sync setting and tap the toggle to disable it.
Mute Gmail notifications
You can also disable notifications for your account in Gmail by keeping signed in and syncing but mute notifications.
Open In the Gmail app, tap the hamburger menu icon in the upper-left corner to access the page menu, scroll down, and tap Settings.
Find and tap Notifications on your account and in the settings area for your account.
Change the notification intensity for your account to "All." to "none". Alternatively, you can select "High P Priority Only" if you want to allow notifications for your most important e-mails.
If you select None, notifications for your Gmail account will be muted. You will still receive tacit emails if you need to review them in the future.
Removing Your Gmail Account
If you're determined to remove your Gmail account from your device, you can do so in a few simple steps. You should take this into account when changing to a brand new Gmail account or when transferring your device to someone else.
First, open your device's Settings menu by flicking down the notification shadow and tapping the gearwheel icon.
On the Settings menu, tap Accounts. This section may display the label "Accounts and Backup" or a similar label device that you own.
Find and press your Google Account to open the account settings. Touch "Remove account" to start the process.
button You will be asked to confirm the removal by clicking "Remove Account" one last time. 
Once you tap it, your Gmail account will be removed from your device. You will not be able to access it in Gmail or other Google services.
Remotely removing your Gmail account
If you have lost your Android device or it has been stolen, you will be able to remove your account remotely from your Google Account settings online. For this you need another device, eg. A computer.
Sign in to the web using another device in your Google Account. Click on "Security" in the left menu.
Scroll down to "Your Devices" and click "Manage Devices."
The list of devices that your Google Account is signed in to appears. Click on the missing device and under "Account Access" click the "Remove" button.
You will receive a warning message asking you to remove your account. Click on "Remove" to confirm.
You will receive a confirmation that your account has been removed from your device.
This way, you will be logged out of your device but not completely removed. A warning message will appear on your device asking you to reenter your password to restore access.
To completely remove all traces of your account from your device at this point, follow the steps above. Go to your Android Settings, go to Settings> Accounts, and search for your Google Account. Click on "Remove Account" and confirm to completely remove it.
The final trace of your Gmail account will then be completely removed from yours
This is important if you have lost your Android device or want to sell it. You do not need to remove your Gmail account if you want to add a second account. You can be logged in to any number of accounts.
However, if you need to remove your Gmail account, this should not be the case for more than a few minutes from start to finish.