How to lock Google sheet cell after someone has verified it?

See more:

Javascript

Google

For example, person A input data in A1&A2, then when person B verify it by putting "/" on A3, it will remove person A editing A1&A2 data.

What I have tried:

I have only learned python and totally new to javascript.

But the logic should be something like this.

If cell A3 == '/':

RemoveEditors(test123@gmail.com) in range(A1:A2)