Open Gmail
Click your profile picture in the top-right corner
Click “Sign out” or “Sign out of all accounts”
If you are on a browser, close the browser after signing out
If you are using the Gmail app, remove the account from your device settings if needed
On Android, go to Settings > Passwords & accounts or Accounts > Google > Remove account
On iPhone, open the Gmail app, tap your profile picture, tap “Manage accounts on this device,” then remove the account
If you want to sign out from all devices, go to your Google Account security settings and remove access from devices you no longer use