Sometimes we have an error like below when we try to push on Github.

Try to check where is your ssh key is being used by the following command:

 ssh -T -ai ~/.ssh/id_rsa [email protected]

You will get a response like this:

So, in my case, my ssh key was being used by my other GitHub account. Now you have 2 choices.

1. Remove ssh key from other account and add to your account where you are trying to push
2. Generate new ssh key and use it.

I did 1st as It was not needed for my other account.