Hello Lakshanya,
Try going to account.microsoft.com/family and see if you can leave the family group. If that doesn’t work, go to account.microsoft.com/profile, edit your birthdate to make yourself 18 or older, then sign out and back in. This might let you leave the group. If you're still stuck, the best next step is to contact Microsoft Support directly at support.microsoft.com/contactus. Choose “Microsoft account” > “Family & child safety” > “Manage family group,” and request a chat or call.
Explain that your account is stuck in a family group because the organizer account was deleted, and you need help removing it. In the meantime, if you urgently need Chrome for school, you can try going to C:\Program Files\Google\Chrome\Application, find chrome.exe, right-click and rename it to chrome1.exe, then open it—this can sometimes bypass the Family Safety block temporarily.