Create a text file and name it whatever you like. Inside it, put the following text:
||id.google.com^
||accounts.google.com/gsi/$3p
||smartlock.google.com^
! Block “Sign in with Google” iframe in top right corner of websites
||accounts.google.com/gsi/iframe
Then save it and go to uBlock’s settings, then to ‘My filters’ – ‘Import’ – select the file you just created – ‘Apply changes.’
After that, clear all cookies and other data from your browser – Done!
Enjoy life without annoying Google stuff!