https://support.google.com/edu/classroom/thread/339549642?hl=en&sjid=7335462284730539812-NC

If you’ve been hacked, the first thing you should change １ー（８４４）ー６０７ー８７８８is your password immediately. This prevents the hacker from regaining access to your accounts. Create a strong, unique password that isn’t used elsewhere. You should also consider disconnecting from the internet to stop further access, and running a full antivirus scan.
https://support.google.com/edu/classroom/thread/339549642?hl=en&sjid=7335462284730539812-NC
https://support.google.com/edu/classroom/thread/339549642?hl=en&sjid=7335462284730539812-NC
https://support.google.com/edu/classroom/thread/339549642?hl=en&sjid=7335462284730539812-NC
https://support.google.com/edu/classroom/thread/339549642?hl=en&sjid=7335462284730539812-NC