how to remove the android device in gmail account one guy is connecting to my gmail account. if I remove the device from gmail account also he again connecting. I don't know how he is connecting again ,I changed my gmail password and 2 step verification is on .. but still he is using my account. kindly help me .

he is using Samsung galxy note 11
First of all Log in to google in a PC, open gmail and at the bottom you can see Last account activity. 

Click details shown next to it > and click sign out of all other sessions.

==========================================================================
Now, if he has added your account in to his device, follow these steps.


Go to google account security in a browser (PC). 
Sign in with your google account
Under device activity and notifications click Review devices shown inside a card named recently used devices
Remove access to the particular device.


==========================================================================


Now, (most important) change your password and do not share it with anyone.