Steps to change your profile name:
1. Click on the circle on the top right corner of the Google home page, i.e., https://www.google.co.in/
2. A menu will appear in which there will be an option — Manage your Google Account — Select that option. It will take you to the Google Account page.
3. On the left side there is an option — Personal info — Click on that.
4. A page will load where you will be able to find an option — Name — click on that to open a page where you can change your name.
5. Change the First name to your "<Subject code><Roll number> - <Last name> <First Name>" and click Save.
Note: Subject code is specific 'Three letter code [XYZ]' for each subject combination. The subject code will be provided by the college.
6. Go back to the Home menu and the changed name should be visible.
Note: any non-four digit roll number should be written in four digits, e.g., roll number 1 to be written as '0001'.
So it will be "XYZ0001 - Last name First Name".