Cannot Edit fstab as it is a Read-Only File

1. How to edit read only fstab?
2. How to edit /etc/fstab when system boots to read only file system?

Issue

/etc/fstab has been messed up. It is read-only now.

Tried

mount -o remount,rw /

Does not work

Solutions

mount -o remount,rw /dev/sda2 /

Note: Instead of /dev/sda2, use whatever the device is valid for your drive.